diff --git a/eng/testing/tests.browser.targets b/eng/testing/tests.browser.targets
index 26a2086c850b5..3ff4c3b507763 100644
--- a/eng/testing/tests.browser.targets
+++ b/eng/testing/tests.browser.targets
@@ -93,8 +93,6 @@
     <_AppArgs Condition="'$(IsFunctionalTest)' != 'true' and '$(WasmMainAssemblyFileName)' != ''">--run $(WasmMainAssemblyFileName)</_AppArgs>
     <_AppArgs Condition="'$(IsFunctionalTest)' == 'true'">--run $(AssemblyName).dll</_AppArgs>
 
-    <WasmTestAppArgs Condition="'$(_XUnitBackgroundExec)' == 'true'">$(WasmTestAppArgs) -backgroundExec</WasmTestAppArgs>
-    <WasmXHarnessMonoArgs Condition="'$(_XUnitBackgroundExec)' == 'true'">$(WasmXHarnessMonoArgs) --setenv=IsWasmBackgroundExec=true</WasmXHarnessMonoArgs>
     <_AppArgs Condition="'$(WasmTestAppArgs)' != ''">$(_AppArgs) $(WasmTestAppArgs)</_AppArgs>
 
     <WasmXHarnessMonoArgs Condition="'$(XunitShowProgress)' == 'true'">$(WasmXHarnessMonoArgs) --setenv=XHARNESS_LOG_TEST_START=true</WasmXHarnessMonoArgs>
diff --git a/src/libraries/Common/tests/System/TimeProviderTests.cs b/src/libraries/Common/tests/System/TimeProviderTests.cs
index 7a0cb33eb74d7..428c5b13fecc5 100644
--- a/src/libraries/Common/tests/System/TimeProviderTests.cs
+++ b/src/libraries/Common/tests/System/TimeProviderTests.cs
@@ -214,7 +214,7 @@ private static void CancelAfter(TimeProvider provider, CancellationTokenSource c
         }
 #endif // NETFRAMEWORK
 
-        [ConditionalTheory(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupportedOrBrowserBackgroundExec))]
+        [ConditionalTheory(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupported))]
         [MemberData(nameof(TimersProvidersListData))]
         public static void CancellationTokenSourceWithTimer(TimeProvider provider)
         {
diff --git a/src/libraries/Common/tests/TestUtilities/System/PlatformDetection.cs b/src/libraries/Common/tests/TestUtilities/System/PlatformDetection.cs
index 8aac858961109..c76a1ee94d975 100644
--- a/src/libraries/Common/tests/TestUtilities/System/PlatformDetection.cs
+++ b/src/libraries/Common/tests/TestUtilities/System/PlatformDetection.cs
@@ -135,10 +135,6 @@ public static int SlowRuntimeTimeoutModifier
         public static bool IsThreadingSupported => (!IsWasi && !IsBrowser) || IsWasmThreadingSupported;
         public static bool IsWasmThreadingSupported => IsBrowser && IsEnvironmentVariableTrue("IsBrowserThreadingSupported");
         public static bool IsNotWasmThreadingSupported => !IsWasmThreadingSupported;
-        public static bool IsWasmBackgroundExec => IsBrowser && IsEnvironmentVariableTrue("IsWasmBackgroundExec");
-        public static bool IsThreadingSupportedNotBrowserBackgroundExec => IsWasmThreadingSupported && !IsWasmBackgroundExec;
-        public static bool IsWasmBackgroundExecOrSingleThread => IsWasmBackgroundExec || IsNotWasmThreadingSupported;
-        public static bool IsThreadingSupportedOrBrowserBackgroundExec => IsWasmBackgroundExec || !IsBrowser;
         public static bool IsBinaryFormatterSupported => IsNotMobile && !IsNativeAot;
 
         public static bool IsStartingProcessesSupported => !IsiOS && !IstvOS;
diff --git a/src/libraries/Common/tests/WasmTestRunner/WasmTestRunner.cs b/src/libraries/Common/tests/WasmTestRunner/WasmTestRunner.cs
index 9935182c69d03..98798cba791a7 100644
--- a/src/libraries/Common/tests/WasmTestRunner/WasmTestRunner.cs
+++ b/src/libraries/Common/tests/WasmTestRunner/WasmTestRunner.cs
@@ -29,7 +29,6 @@ public static async Task<int> Main(string[] args)
         var includedNamespaces = new List<string>();
         var includedClasses = new List<string>();
         var includedMethods = new List<string>();
-        var backgroundExec = false;
         var untilFailed = false;
 
         for (int i = 1; i < args.Length; i++)
@@ -57,9 +56,6 @@ public static async Task<int> Main(string[] args)
                     includedMethods.Add(args[i + 1]);
                     i++;
                     break;
-                case "-backgroundExec":
-                    backgroundExec = true;
-                    break;
                 case "-untilFailed":
                     untilFailed = true;
                     break;
@@ -94,14 +90,7 @@ public static async Task<int> Main(string[] args)
         var res = 0;
         do
         {
-            if (backgroundExec)
-            {
-                res = await Task.Run(() => runner.Run());
-            }
-            else
-            {
-                res = await runner.Run();
-            }
+            res = await runner.Run();
         }
         while(res == 0 && untilFailed);
 
diff --git a/src/libraries/Microsoft.Extensions.DependencyInjection/tests/DI.Tests/ServiceLookup/CallSiteFactoryTest.cs b/src/libraries/Microsoft.Extensions.DependencyInjection/tests/DI.Tests/ServiceLookup/CallSiteFactoryTest.cs
index 74f85296af952..919dee6475909 100644
--- a/src/libraries/Microsoft.Extensions.DependencyInjection/tests/DI.Tests/ServiceLookup/CallSiteFactoryTest.cs
+++ b/src/libraries/Microsoft.Extensions.DependencyInjection/tests/DI.Tests/ServiceLookup/CallSiteFactoryTest.cs
@@ -792,7 +792,7 @@ public void CreateCallSite_EnumberableCachedAtLowestLevel(ServiceDescriptor[] de
             Assert.Equal(typeof(IEnumerable<FakeService>), callSite.Cache.Key.ServiceIdentifier.ServiceType);
         }
 
-        [ConditionalFact(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupportedOrBrowserBackgroundExec))]
+        [ConditionalFact(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupported))]
         public void CallSitesAreUniquePerServiceTypeAndSlot()
         {
             // Connected graph
@@ -828,7 +828,7 @@ public void CallSitesAreUniquePerServiceTypeAndSlot()
             }
         }
 
-        [ConditionalFact(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupportedOrBrowserBackgroundExec))]
+        [ConditionalFact(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupported))]
         public void CallSitesAreUniquePerServiceTypeAndSlotWithOpenGenericInGraph()
         {
             // Connected graph
diff --git a/src/libraries/Microsoft.Extensions.DependencyInjection/tests/DI.Tests/ServiceProviderContainerTests.cs b/src/libraries/Microsoft.Extensions.DependencyInjection/tests/DI.Tests/ServiceProviderContainerTests.cs
index f668cee41efc3..3e08a16db282e 100644
--- a/src/libraries/Microsoft.Extensions.DependencyInjection/tests/DI.Tests/ServiceProviderContainerTests.cs
+++ b/src/libraries/Microsoft.Extensions.DependencyInjection/tests/DI.Tests/ServiceProviderContainerTests.cs
@@ -371,7 +371,7 @@ public void GetService_DisposeOnSameThread_Throws()
             });
         }
 
-        [ConditionalFact(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupportedOrBrowserBackgroundExec))]
+        [ConditionalFact(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupported))]
         public void GetAsyncService_DisposeAsyncOnSameThread_ThrowsAndDoesNotHangAndDisposeAsyncGetsCalled()
         {
             // Arrange
@@ -398,7 +398,7 @@ public void GetAsyncService_DisposeAsyncOnSameThread_ThrowsAndDoesNotHangAndDisp
             Assert.True(asyncDisposableResource.DisposeAsyncCalled);
         }
 
-        [ConditionalFact(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupportedOrBrowserBackgroundExec))]
+        [ConditionalFact(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupported))]
         public void GetService_DisposeOnSameThread_ThrowsAndDoesNotHangAndDisposeGetsCalled()
         {
             // Arrange
diff --git a/src/libraries/Microsoft.Extensions.HostFactoryResolver/tests/HostFactoryResolverTests.cs b/src/libraries/Microsoft.Extensions.HostFactoryResolver/tests/HostFactoryResolverTests.cs
index f123b65bb58bc..e95a745a5259c 100644
--- a/src/libraries/Microsoft.Extensions.HostFactoryResolver/tests/HostFactoryResolverTests.cs
+++ b/src/libraries/Microsoft.Extensions.HostFactoryResolver/tests/HostFactoryResolverTests.cs
@@ -37,7 +37,7 @@ public void BuildWebHostPattern_CanFindServiceProvider()
             Assert.IsAssignableFrom<IServiceProvider>(factory(Array.Empty<string>()));
         }
 
-        [ConditionalFact(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupportedOrBrowserBackgroundExec))]
+        [ConditionalFact(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupported))]
         [DynamicDependency(DynamicallyAccessedMemberTypes.All, typeof(BuildWebHostInvalidSignature.Program))]
         public void BuildWebHostPattern__Invalid_CantFindWebHost()
         {
@@ -46,7 +46,7 @@ public void BuildWebHostPattern__Invalid_CantFindWebHost()
             Assert.Null(factory);
         }
 
-        [ConditionalFact(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupportedOrBrowserBackgroundExec))]
+        [ConditionalFact(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupported))]
         [DynamicDependency(DynamicallyAccessedMemberTypes.All, typeof(BuildWebHostInvalidSignature.Program))]
         public void BuildWebHostPattern__Invalid_CantFindServiceProvider()
         {
@@ -55,7 +55,7 @@ public void BuildWebHostPattern__Invalid_CantFindServiceProvider()
             Assert.NotNull(factory);
         }
 
-        [ConditionalFact(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupportedOrBrowserBackgroundExec))]
+        [ConditionalFact(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupported))]
         [DynamicDependency(DynamicallyAccessedMemberTypes.All, typeof(CreateWebHostBuilderPatternTestSite.Program))]
         public void CreateWebHostBuilderPattern_CanFindWebHostBuilder()
         {
@@ -65,7 +65,7 @@ public void CreateWebHostBuilderPattern_CanFindWebHostBuilder()
             Assert.IsAssignableFrom<IWebHostBuilder>(factory(Array.Empty<string>()));
         }
 
-        [ConditionalFact(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupportedOrBrowserBackgroundExec))]
+        [ConditionalFact(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupported))]
         [DynamicDependency(DynamicallyAccessedMemberTypes.All, typeof(CreateWebHostBuilderPatternTestSite.Program))]
         [DynamicDependency(DynamicallyAccessedMemberTypes.All, typeof(IWebHost))]
         public void CreateWebHostBuilderPattern_CanFindServiceProvider()
@@ -76,7 +76,7 @@ public void CreateWebHostBuilderPattern_CanFindServiceProvider()
             Assert.IsAssignableFrom<IServiceProvider>(factory(Array.Empty<string>()));
         }
 
-        [ConditionalFact(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupportedOrBrowserBackgroundExec))]
+        [ConditionalFact(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupported))]
         [DynamicDependency(DynamicallyAccessedMemberTypes.All, typeof(CreateWebHostBuilderInvalidSignature.Program))]
         public void CreateWebHostBuilderPattern__Invalid_CantFindWebHostBuilder()
         {
@@ -85,7 +85,7 @@ public void CreateWebHostBuilderPattern__Invalid_CantFindWebHostBuilder()
             Assert.Null(factory);
         }
 
-        [ConditionalFact(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupportedOrBrowserBackgroundExec))]
+        [ConditionalFact(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupported))]
         [DynamicDependency(DynamicallyAccessedMemberTypes.All, typeof(CreateWebHostBuilderInvalidSignature.Program))]
         public void CreateWebHostBuilderPattern__InvalidReturnType_CanFindServiceProvider()
         {
@@ -95,7 +95,7 @@ public void CreateWebHostBuilderPattern__InvalidReturnType_CanFindServiceProvide
             Assert.Null(factory(Array.Empty<string>()));
         }
 
-        [ConditionalFact(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupportedOrBrowserBackgroundExec))]
+        [ConditionalFact(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupported))]
         [DynamicDependency(DynamicallyAccessedMemberTypes.All, typeof(CreateHostBuilderPatternTestSite.Program))]
         public void CreateHostBuilderPattern_CanFindHostBuilder()
         {
@@ -105,7 +105,7 @@ public void CreateHostBuilderPattern_CanFindHostBuilder()
             Assert.IsAssignableFrom<IHostBuilder>(factory(Array.Empty<string>()));
         }
 
-        [ConditionalFact(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupportedOrBrowserBackgroundExec))]
+        [ConditionalFact(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupported))]
         [DynamicDependency(DynamicallyAccessedMemberTypes.All, typeof(CreateHostBuilderPatternTestSite.Program))]
         [DynamicDependency(DynamicallyAccessedMemberTypes.All, typeof(Host))]
         public void CreateHostBuilderPattern_CanFindServiceProvider()
@@ -116,7 +116,7 @@ public void CreateHostBuilderPattern_CanFindServiceProvider()
             Assert.IsAssignableFrom<IServiceProvider>(factory(Array.Empty<string>()));
         }
 
-        [ConditionalFact(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupportedOrBrowserBackgroundExec))]
+        [ConditionalFact(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupported))]
         [DynamicDependency(DynamicallyAccessedMemberTypes.All, typeof(CreateHostBuilderInvalidSignature.Program))]
         public void CreateHostBuilderPattern__Invalid_CantFindHostBuilder()
         {
@@ -125,7 +125,7 @@ public void CreateHostBuilderPattern__Invalid_CantFindHostBuilder()
             Assert.Null(factory);
         }
 
-        [ConditionalFact(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupportedOrBrowserBackgroundExec))]
+        [ConditionalFact(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupported))]
         [DynamicDependency(DynamicallyAccessedMemberTypes.All, typeof(CreateHostBuilderInvalidSignature.Program))]
         public void CreateHostBuilderPattern__Invalid_CantFindServiceProvider()
         {
@@ -135,7 +135,7 @@ public void CreateHostBuilderPattern__Invalid_CantFindServiceProvider()
             Assert.Throws<InvalidOperationException>(() => factory(Array.Empty<string>()));
         }
 
-        [ConditionalFact(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupportedOrBrowserBackgroundExec))]
+        [ConditionalFact(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupported))]
         [DynamicDependency(DynamicallyAccessedMemberTypes.All, typeof(NoSpecialEntryPointPattern.Program))]
         public void NoSpecialEntryPointPattern()
         {
@@ -145,7 +145,7 @@ public void NoSpecialEntryPointPattern()
             Assert.IsAssignableFrom<IServiceProvider>(factory(Array.Empty<string>()));
         }
 
-        [ConditionalFact(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupportedOrBrowserBackgroundExec))]
+        [ConditionalFact(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupported))]
         [DynamicDependency(DynamicallyAccessedMemberTypes.All, typeof(NoSpecialEntryPointPattern.Program))]
         public void NoSpecialEntryPointPatternHostBuilderConfigureHostBuilderCallbackIsCalled()
         {
@@ -163,7 +163,7 @@ void ConfigureHostBuilder(object hostBuilder)
             Assert.True(called);
         }
 
-        [ConditionalFact(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupportedOrBrowserBackgroundExec))]
+        [ConditionalFact(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupported))]
         [DynamicDependency(DynamicallyAccessedMemberTypes.All, typeof(NoSpecialEntryPointPattern.Program))]
         public void NoSpecialEntryPointPatternBuildsThenThrowsCallsEntryPointCompletedCallback()
         {
@@ -183,7 +183,7 @@ void EntryPointCompleted(Exception? exception)
             Assert.Null(entryPointException);
         }
 
-        [ConditionalFact(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupportedOrBrowserBackgroundExec))]
+        [ConditionalFact(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupported))]
         [DynamicDependency(DynamicallyAccessedMemberTypes.All, typeof(NoSpecialEntryPointPatternBuildsThenThrows.Program))]
         public void NoSpecialEntryPointPatternBuildsThenThrowsCallsEntryPointCompletedCallbackWithException()
         {
@@ -203,7 +203,7 @@ void EntryPointCompleted(Exception? exception)
             Assert.NotNull(entryPointException);
         }
 
-        [ConditionalFact(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupportedOrBrowserBackgroundExec))]
+        [ConditionalFact(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupported))]
         [DynamicDependency(DynamicallyAccessedMemberTypes.All, typeof(NoSpecialEntryPointPatternThrows.Program))]
         public void NoSpecialEntryPointPatternThrows()
         {
@@ -213,7 +213,7 @@ public void NoSpecialEntryPointPatternThrows()
             Assert.Throws<Exception>(() => factory(Array.Empty<string>()));
         }
 
-        [ConditionalFact(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupportedOrBrowserBackgroundExec))]
+        [ConditionalFact(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupported))]
         [DynamicDependency(DynamicallyAccessedMemberTypes.All, typeof(NoSpecialEntryPointPatternExits.Program))]
         public void NoSpecialEntryPointPatternExits()
         {
@@ -223,7 +223,7 @@ public void NoSpecialEntryPointPatternExits()
             Assert.Throws<InvalidOperationException>(() => factory(Array.Empty<string>()));
         }
 
-        [ConditionalFact(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupportedOrBrowserBackgroundExec))]
+        [ConditionalFact(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupported))]
         [DynamicDependency(DynamicallyAccessedMemberTypes.All, typeof(NoSpecialEntryPointPatternHangs.Program))]
         public void NoSpecialEntryPointPatternHangs()
         {
@@ -233,7 +233,7 @@ public void NoSpecialEntryPointPatternHangs()
             Assert.Throws<InvalidOperationException>(() => factory(Array.Empty<string>()));
         }
 
-        [ConditionalFact(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupportedOrBrowserBackgroundExec))]
+        [ConditionalFact(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupported))]
         [DynamicDependency(DynamicallyAccessedMemberTypes.All, typeof(NoSpecialEntryPointPatternMainNoArgs.Program))]
         public void NoSpecialEntryPointPatternMainNoArgs()
         {
@@ -243,7 +243,7 @@ public void NoSpecialEntryPointPatternMainNoArgs()
             Assert.IsAssignableFrom<IServiceProvider>(factory(Array.Empty<string>()));
         }
 
-        [ConditionalFact(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupportedOrBrowserBackgroundExec))]
+        [ConditionalFact(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupported))]
         [DynamicDependency(DynamicallyAccessedMemberTypes.All, "Program", "TopLevelStatements")]
         public void TopLevelStatements()
         {
@@ -254,7 +254,7 @@ public void TopLevelStatements()
             Assert.IsAssignableFrom<IServiceProvider>(factory(Array.Empty<string>()));
         }
 
-        [ConditionalFact(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupportedOrBrowserBackgroundExec))]
+        [ConditionalFact(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupported))]
         [DynamicDependency(DynamicallyAccessedMemberTypes.All, "Program", "TopLevelStatementsTestsTimeout")]
         public void TopLevelStatementsTestsTimeout()
         {
@@ -265,7 +265,7 @@ public void TopLevelStatementsTestsTimeout()
             Assert.Throws<InvalidOperationException>(() => factory(Array.Empty<string>()));
         }
 
-        [ConditionalFact(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupportedOrBrowserBackgroundExec))]
+        [ConditionalFact(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupported))]
         [DynamicDependency(DynamicallyAccessedMemberTypes.All, "Program", "ApplicationNameSetFromArgument")]
         public void ApplicationNameSetFromArgument()
         {
@@ -277,7 +277,7 @@ public void ApplicationNameSetFromArgument()
             Assert.Contains("ApplicationNameSetFromArgument", configuration["applicationName"]);
         }
 
-        [ConditionalFact(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupportedOrBrowserBackgroundExec))]
+        [ConditionalFact(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupported))]
         [DynamicDependency(DynamicallyAccessedMemberTypes.All, typeof(NoSpecialEntryPointPattern.Program))]
         public void NoSpecialEntryPointPatternCanRunInParallel()
         {
diff --git a/src/libraries/Microsoft.Extensions.Http/tests/Microsoft.Extensions.Http.Tests/DependencyInjection/HttpClientFactoryServiceCollectionExtensionsTest.cs b/src/libraries/Microsoft.Extensions.Http/tests/Microsoft.Extensions.Http.Tests/DependencyInjection/HttpClientFactoryServiceCollectionExtensionsTest.cs
index 81bb589fcfb31..c72b17e728848 100644
--- a/src/libraries/Microsoft.Extensions.Http/tests/Microsoft.Extensions.Http.Tests/DependencyInjection/HttpClientFactoryServiceCollectionExtensionsTest.cs
+++ b/src/libraries/Microsoft.Extensions.Http/tests/Microsoft.Extensions.Http.Tests/DependencyInjection/HttpClientFactoryServiceCollectionExtensionsTest.cs
@@ -1203,7 +1203,7 @@ public async Task AddHttpClient_MessageHandler_Scope_TransientDependency()
             }
         }
 
-        [ConditionalFact(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupportedOrBrowserBackgroundExec), nameof(PlatformDetection.IsReflectionEmitSupported))]
+        [ConditionalFact(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupported), nameof(PlatformDetection.IsReflectionEmitSupported))]
         public void AddHttpClient_GetAwaiterAndResult_InSingleThreadedSynchronizationContext_ShouldNotHangs()
         {
             // Arrange
diff --git a/src/libraries/System.IO.Pipelines/tests/PipeWriterTests.cs b/src/libraries/System.IO.Pipelines/tests/PipeWriterTests.cs
index 2913efbe3cdf6..85070e1534a8e 100644
--- a/src/libraries/System.IO.Pipelines/tests/PipeWriterTests.cs
+++ b/src/libraries/System.IO.Pipelines/tests/PipeWriterTests.cs
@@ -294,7 +294,6 @@ public async Task WritesUsingGetMemoryWorks()
         }
 
         [ConditionalFact(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupported))]
-        [ActiveIssue("https://github.com/dotnet/runtime/issues/91547", typeof(PlatformDetection), nameof(PlatformDetection.IsWasmThreadingSupported))]
         public async Task CompleteWithLargeWriteThrows()
         {
             var completeDelay = TimeSpan.FromMilliseconds(10);
diff --git a/src/libraries/System.Runtime.InteropServices.JavaScript/tests/System.Runtime.InteropServices.JavaScript.UnitTests/System/Runtime/InteropServices/JavaScript/JSExportTest.cs b/src/libraries/System.Runtime.InteropServices.JavaScript/tests/System.Runtime.InteropServices.JavaScript.UnitTests/System/Runtime/InteropServices/JavaScript/JSExportTest.cs
index 170f393deb7c6..d8c3f71ff73ec 100644
--- a/src/libraries/System.Runtime.InteropServices.JavaScript/tests/System.Runtime.InteropServices.JavaScript.UnitTests/System/Runtime/InteropServices/JavaScript/JSExportTest.cs
+++ b/src/libraries/System.Runtime.InteropServices.JavaScript/tests/System.Runtime.InteropServices.JavaScript.UnitTests/System/Runtime/InteropServices/JavaScript/JSExportTest.cs
@@ -14,7 +14,7 @@ namespace System.Runtime.InteropServices.JavaScript.Tests
 {
     public class JSExportAsyncTest : JSInteropTestBase, IAsyncLifetime
     {
-        [ConditionalFact(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupportedNotBrowserBackgroundExec))]
+        [ConditionalFact(typeof(PlatformDetection), nameof(PlatformDetection.IsWasmThreadingSupported))]
         public void SyncJsImportJsExportThrows()
         {
             var ex = Assert.Throws<JSException>(()=>JavaScriptTestHelper.invoke1_Boolean(true, nameof(JavaScriptTestHelper.EchoBoolean)));
@@ -50,7 +50,7 @@ public async Task JsExportInt32DiscardNoWait(int value)
         }
     }
 
-    [ConditionalClass(typeof(PlatformDetection), nameof(PlatformDetection.IsWasmBackgroundExecOrSingleThread))]
+    [ConditionalClass(typeof(PlatformDetection), nameof(PlatformDetection.IsNotWasmThreadingSupported))]
     public class JSExportTest : JSInteropTestBase, IAsyncLifetime
     {
         [Theory]
@@ -157,7 +157,6 @@ public void JsExportIntPtr(IntPtr value)
         [MemberData(nameof(MarshalIntPtrCases))]
         public unsafe void JsExportVoidPtr(IntPtr xvalue)
         {
-            JavaScriptTestHelper.AssertWasmBackgroundExec();
             void* value = (void*)xvalue;
             void* res = JavaScriptTestHelper.invoke1_VoidPtr(value, nameof(JavaScriptTestHelper.EchoVoidPtr));
             Assert.True(value == res);
@@ -188,7 +187,6 @@ public void JsExportDateTimeOffset(DateTimeOffset value)
         [MemberData(nameof(MarshalNullableBooleanCases))]
         public void JsExportNullableBoolean(bool? value)
         {
-            JavaScriptTestHelper.AssertWasmBackgroundExec();
             JsExportTest(value,
                 JavaScriptTestHelper.invoke1_NullableBoolean,
                 nameof(JavaScriptTestHelper.EchoNullableBoolean),
diff --git a/src/libraries/System.Runtime.InteropServices.JavaScript/tests/System.Runtime.InteropServices.JavaScript.UnitTests/System/Runtime/InteropServices/JavaScript/JSImportTest.cs b/src/libraries/System.Runtime.InteropServices.JavaScript/tests/System.Runtime.InteropServices.JavaScript.UnitTests/System/Runtime/InteropServices/JavaScript/JSImportTest.cs
index 632b27b105c94..140fd8f0248f8 100644
--- a/src/libraries/System.Runtime.InteropServices.JavaScript/tests/System.Runtime.InteropServices.JavaScript.UnitTests/System/Runtime/InteropServices/JavaScript/JSImportTest.cs
+++ b/src/libraries/System.Runtime.InteropServices.JavaScript/tests/System.Runtime.InteropServices.JavaScript.UnitTests/System/Runtime/InteropServices/JavaScript/JSImportTest.cs
@@ -127,10 +127,9 @@ public unsafe void OutOfRange()
             Assert.Contains("Overflow: value 9007199254740991 is out of -2147483648 2147483647 range", ex.Message);
         }
 
-        [ConditionalFact(typeof(PlatformDetection), nameof(PlatformDetection.IsWasmBackgroundExecOrSingleThread))]
+        [ConditionalFact(typeof(PlatformDetection), nameof(PlatformDetection.IsNotWasmThreadingSupported))]
         public unsafe void OptimizedPaths()
         {
-            JavaScriptTestHelper.AssertWasmBackgroundExec();
             JavaScriptTestHelper.optimizedReached = 0;
             JavaScriptTestHelper.invoke0V();
             Assert.Equal(1, JavaScriptTestHelper.optimizedReached);
diff --git a/src/libraries/System.Runtime.InteropServices.JavaScript/tests/System.Runtime.InteropServices.JavaScript.UnitTests/System/Runtime/InteropServices/JavaScript/JavaScriptTestHelper.cs b/src/libraries/System.Runtime.InteropServices.JavaScript/tests/System.Runtime.InteropServices.JavaScript.UnitTests/System/Runtime/InteropServices/JavaScript/JavaScriptTestHelper.cs
index c64be2635a56e..f78a4105e05ab 100644
--- a/src/libraries/System.Runtime.InteropServices.JavaScript/tests/System.Runtime.InteropServices.JavaScript.UnitTests/System/Runtime/InteropServices/JavaScript/JavaScriptTestHelper.cs
+++ b/src/libraries/System.Runtime.InteropServices.JavaScript/tests/System.Runtime.InteropServices.JavaScript.UnitTests/System/Runtime/InteropServices/JavaScript/JavaScriptTestHelper.cs
@@ -1028,24 +1028,14 @@ public static JSObject EchoIJSObject([JSMarshalAs<JSType.Object>] JSObject arg1)
         [JSImport("INTERNAL.forceDisposeProxies")]
         internal static partial void ForceDisposeProxies(bool disposeMethods, bool verbose);
 
-        public static void AssertWasmBackgroundExec()
-        {
-            if (PlatformDetection.IsWasmBackgroundExec && Environment.CurrentManagedThreadId == 1)
-            {
-                throw new Exception("With WasmBackgroundExec we are expecting to run tests on the thread pool");
-            }
-        }
-
         static JSObject _module;
         public static async Task InitializeAsync()
         {
-            AssertWasmBackgroundExec();
             if (_module == null)
             {
                 _module = await JSHost.ImportAsync("JavaScriptTestHelper", "../JavaScriptTestHelper.mjs"); ;
                 await Setup();
             }
-            AssertWasmBackgroundExec();
 
 #if FEATURE_WASM_MANAGED_THREADS
             // are we in the UI thread ?
@@ -1055,7 +1045,6 @@ public static async Task InitializeAsync()
                 // this gives browser chance to serve UI thread event loop before every test
                 await Task.Yield();
             }
-            AssertWasmBackgroundExec();
         }
 
         public static Task DisposeAsync()
diff --git a/src/libraries/System.Runtime/tests/System.Buffers.Tests/ArrayPool/UnitTests.cs b/src/libraries/System.Runtime/tests/System.Buffers.Tests/ArrayPool/UnitTests.cs
index d58a8838d90a9..70f38687102d7 100644
--- a/src/libraries/System.Runtime/tests/System.Buffers.Tests/ArrayPool/UnitTests.cs
+++ b/src/libraries/System.Runtime/tests/System.Buffers.Tests/ArrayPool/UnitTests.cs
@@ -272,7 +272,7 @@ public static void RentingReturningThenRentingABufferShouldNotAllocate()
             Assert.Equal(id, bt.GetHashCode());
         }
 
-        [ConditionalTheory(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupportedOrBrowserBackgroundExec))]
+        [ConditionalTheory(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupported))]
         [MemberData(nameof(BytePoolInstances))]
         public static void CanRentManySizedBuffers(ArrayPool<byte> pool)
         {
diff --git a/src/libraries/System.Runtime/tests/System.Threading.Tasks.Tests/CancellationTokenTests.cs b/src/libraries/System.Runtime/tests/System.Threading.Tasks.Tests/CancellationTokenTests.cs
index bc66b33cd9b68..0d48e3840d96a 100644
--- a/src/libraries/System.Runtime/tests/System.Threading.Tasks.Tests/CancellationTokenTests.cs
+++ b/src/libraries/System.Runtime/tests/System.Threading.Tasks.Tests/CancellationTokenTests.cs
@@ -880,7 +880,6 @@ static void FinalizeHelper(DisposeTracker disposeTracker)
 
         // Several tests for deriving custom user types from CancellationTokenSource
         [ConditionalFact(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupported))]
-        [ActiveIssue("https://github.com/dotnet/runtime/issues/99519", typeof(PlatformDetection), nameof(PlatformDetection.IsWasmThreadingSupported))]
         public static void DerivedCancellationTokenSource()
         {
             // Verify that a derived CTS is functional
diff --git a/src/libraries/System.Runtime/tests/System.Threading.Tasks.Tests/MethodCoverage.cs b/src/libraries/System.Runtime/tests/System.Threading.Tasks.Tests/MethodCoverage.cs
index 01af9fb525c03..695cd6abb1714 100644
--- a/src/libraries/System.Runtime/tests/System.Threading.Tasks.Tests/MethodCoverage.cs
+++ b/src/libraries/System.Runtime/tests/System.Threading.Tasks.Tests/MethodCoverage.cs
@@ -295,7 +295,6 @@ public static async Task Task_WhenAny_TwoTasks_WakesOnFirstCompletion()
         }
 
         [ConditionalFact(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupported))]
-        [ActiveIssue("https://github.com/dotnet/runtime/issues/99500", typeof(PlatformDetection), nameof(PlatformDetection.IsWasmThreadingSupported))]
         public static void CancellationTokenRegitration()
         {
             ManualResetEvent mre = new ManualResetEvent(false);
@@ -313,7 +312,6 @@ public static void CancellationTokenRegitration()
         /// verify that the taskawaiter.UnsafeOnCompleted is invoked
         /// </summary>
         [ConditionalFact(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupported))]
-        [ActiveIssue("https://github.com/dotnet/runtime/issues/99519", typeof(PlatformDetection), nameof(PlatformDetection.IsWasmThreadingSupported))]
         public static void TaskAwaiter()
         {
             ManualResetEvent mre = new ManualResetEvent(false);
diff --git a/src/libraries/System.Runtime/tests/System.Threading.Tasks.Tests/Task/AsyncEnumerableToBlockingEnumerableTests.cs b/src/libraries/System.Runtime/tests/System.Threading.Tasks.Tests/Task/AsyncEnumerableToBlockingEnumerableTests.cs
index 786734ad8391e..0692aedb514f9 100644
--- a/src/libraries/System.Runtime/tests/System.Threading.Tasks.Tests/Task/AsyncEnumerableToBlockingEnumerableTests.cs
+++ b/src/libraries/System.Runtime/tests/System.Threading.Tasks.Tests/Task/AsyncEnumerableToBlockingEnumerableTests.cs
@@ -70,7 +70,6 @@ static async IAsyncEnumerable<int> CreateSourceEnumerable()
         }
 
         [ConditionalFact(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupported))]
-        [ActiveIssue("https://github.com/dotnet/runtime/issues/99519", typeof(PlatformDetection), nameof(PlatformDetection.IsWasmThreadingSupported))]
         public static void AsyncEnumerableWithDelays()
         {
             var source = new InstrumentedAsyncEnumerable<int>(CreateSourceEnumerable());
@@ -105,7 +104,6 @@ static async IAsyncEnumerable<int> CreateSourceEnumerable()
         }
 
         [ConditionalFact(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupported))]
-        [ActiveIssue("https://github.com/dotnet/runtime/issues/99519", typeof(PlatformDetection), nameof(PlatformDetection.IsWasmThreadingSupported))]
         public static void AsyncEnumerableWithException()
         {
             var source = new InstrumentedAsyncEnumerable<int>(CreateSourceEnumerable());
@@ -134,7 +132,6 @@ static async IAsyncEnumerable<int> CreateSourceEnumerable()
         }
 
         [ConditionalFact(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupported))]
-        [ActiveIssue("https://github.com/dotnet/runtime/issues/99519", typeof(PlatformDetection), nameof(PlatformDetection.IsWasmThreadingSupported))]
         public static void AsyncEnumerableWithCancellation()
         {
             var source = new InstrumentedAsyncEnumerable<string>(CreateSourceEnumerable());
diff --git a/src/libraries/System.Runtime/tests/System.Threading.Tasks.Tests/Task/TaskContinueWithTests.cs b/src/libraries/System.Runtime/tests/System.Threading.Tasks.Tests/Task/TaskContinueWithTests.cs
index 76803afb0195a..2800a5e9e24c4 100644
--- a/src/libraries/System.Runtime/tests/System.Threading.Tasks.Tests/Task/TaskContinueWithTests.cs
+++ b/src/libraries/System.Runtime/tests/System.Threading.Tasks.Tests/Task/TaskContinueWithTests.cs
@@ -1076,7 +1076,6 @@ public static void RunContinuationCancelTest_State()
         }
 
         [ConditionalFact(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupported))]
-        [ActiveIssue("https://github.com/dotnet/runtime/issues/99519", typeof(PlatformDetection), nameof(PlatformDetection.IsWasmThreadingSupported))]
         public static void TestNoDeadlockOnContinueWith()
         {
             Debug.WriteLine("TestNoDeadlockOnContinueWith:  shouldn't deadlock if it passes.");
@@ -1256,7 +1255,6 @@ public static void LongContinuationChain_Unwrap_DoesNotStackOverflow()
         }
 
         [ConditionalFact(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupported))]
-        [ActiveIssue("https://github.com/dotnet/runtime/issues/99519", typeof(PlatformDetection), nameof(PlatformDetection.IsWasmThreadingSupported))]
         public static void LongContinuationChain_Await_DoesNotStackOverflow()
         {
             const int DiveDepth = 12_000;
diff --git a/src/libraries/System.Threading.Tasks.Parallel/tests/ParallelForTests.cs b/src/libraries/System.Threading.Tasks.Parallel/tests/ParallelForTests.cs
index 8093dc661b87c..399ba8c63f5e2 100644
--- a/src/libraries/System.Threading.Tasks.Parallel/tests/ParallelForTests.cs
+++ b/src/libraries/System.Threading.Tasks.Parallel/tests/ParallelForTests.cs
@@ -1211,7 +1211,6 @@ public static void RunParallelLoopCancellationTests()
         /// Test to ensure that the task ID can be accessed from inside the task
         /// </summary>
         [ConditionalFact(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupported))]
-        [ActiveIssue("https://github.com/dotnet/runtime/issues/91583", typeof(PlatformDetection), nameof(PlatformDetection.IsWasmThreadingSupported))]
         public static void TaskIDFromExternalContextTest()
         {
             int? withinTaskId = int.MinValue;
diff --git a/src/libraries/System.Threading/tests/SemaphoreSlimTests.cs b/src/libraries/System.Threading/tests/SemaphoreSlimTests.cs
index dfc75fc2a89e6..7aabd01c39f1e 100644
--- a/src/libraries/System.Threading/tests/SemaphoreSlimTests.cs
+++ b/src/libraries/System.Threading/tests/SemaphoreSlimTests.cs
@@ -90,7 +90,6 @@ public static void RunSemaphoreSlimTest1_WaitAsync()
         }
 
         [ConditionalFact(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupported))]
-        [ActiveIssue("https://github.com/dotnet/runtime/issues/99501", typeof(PlatformDetection), nameof(PlatformDetection.IsWasmThreadingSupported))]
         public static void RunSemaphoreSlimTest1_WaitAsync_NegativeCases()
         {
             // Invalid timeout