diff --git a/packages/react-art/src/ReactARTHostConfig.js b/packages/react-art/src/ReactARTHostConfig.js
index cadf311d54ffd..7ae3941c9253a 100644
--- a/packages/react-art/src/ReactARTHostConfig.js
+++ b/packages/react-art/src/ReactARTHostConfig.js
@@ -471,3 +471,7 @@ export function afterActiveInstanceBlur() {
 export function preparePortalMount(portalInstance: any): void {
   // noop
 }
+
+export function detachDeletedInstance(node: Instance): void {
+  // noop
+}
diff --git a/packages/react-dom/src/client/ReactDOMComponentTree.js b/packages/react-dom/src/client/ReactDOMComponentTree.js
index fbf0a81e29064..2afe66035f364 100644
--- a/packages/react-dom/src/client/ReactDOMComponentTree.js
+++ b/packages/react-dom/src/client/ReactDOMComponentTree.js
@@ -43,6 +43,16 @@ const internalEventHandlersKey = '__reactEvents$' + randomKey;
 const internalEventHandlerListenersKey = '__reactListeners$' + randomKey;
 const internalEventHandlesSetKey = '__reactHandles$' + randomKey;
 
+export function detachDeletedInstance(node: Instance): void {
+  // TODO: This function is only called on host components. I don't think all of
+  // these fields are relevant.
+  delete (node: any)[internalInstanceKey];
+  delete (node: any)[internalPropsKey];
+  delete (node: any)[internalEventHandlersKey];
+  delete (node: any)[internalEventHandlerListenersKey];
+  delete (node: any)[internalEventHandlesSetKey];
+}
+
 export function precacheFiberNode(
   hostInst: Fiber,
   node: Instance | TextInstance | SuspenseInstance | ReactScopeInstance,
diff --git a/packages/react-dom/src/client/ReactDOMHostConfig.js b/packages/react-dom/src/client/ReactDOMHostConfig.js
index 156951ac748bc..695242ca50dbb 100644
--- a/packages/react-dom/src/client/ReactDOMHostConfig.js
+++ b/packages/react-dom/src/client/ReactDOMHostConfig.js
@@ -25,6 +25,7 @@ import {
   getInstanceFromNode as getInstanceFromNodeDOMTree,
   isContainerMarkedAsRoot,
 } from './ReactDOMComponentTree';
+export {detachDeletedInstance} from './ReactDOMComponentTree';
 import {hasRole} from './DOMAccessibilityRoles';
 import {
   createElement,
diff --git a/packages/react-native-renderer/src/ReactFabricHostConfig.js b/packages/react-native-renderer/src/ReactFabricHostConfig.js
index 736001a853e63..347ace3b79190 100644
--- a/packages/react-native-renderer/src/ReactFabricHostConfig.js
+++ b/packages/react-native-renderer/src/ReactFabricHostConfig.js
@@ -481,3 +481,7 @@ export function afterActiveInstanceBlur() {
 export function preparePortalMount(portalInstance: Instance): void {
   // noop
 }
+
+export function detachDeletedInstance(node: Instance): void {
+  // noop
+}
diff --git a/packages/react-native-renderer/src/ReactNativeHostConfig.js b/packages/react-native-renderer/src/ReactNativeHostConfig.js
index d626a175d9340..84538532979e1 100644
--- a/packages/react-native-renderer/src/ReactNativeHostConfig.js
+++ b/packages/react-native-renderer/src/ReactNativeHostConfig.js
@@ -538,3 +538,7 @@ export function afterActiveInstanceBlur() {
 export function preparePortalMount(portalInstance: Instance): void {
   // noop
 }
+
+export function detachDeletedInstance(node: Instance): void {
+  // noop
+}
diff --git a/packages/react-noop-renderer/src/createReactNoop.js b/packages/react-noop-renderer/src/createReactNoop.js
index 80c888a88e53d..dd304fce6d878 100644
--- a/packages/react-noop-renderer/src/createReactNoop.js
+++ b/packages/react-noop-renderer/src/createReactNoop.js
@@ -420,6 +420,8 @@ function createReactNoop(reconciler: Function, useMutation: boolean) {
     getInstanceFromScope() {
       throw new Error('Not yet implemented.');
     },
+
+    detachDeletedInstance() {},
   };
 
   const hostConfig = useMutation
diff --git a/packages/react-reconciler/src/ReactFiberCommitWork.new.js b/packages/react-reconciler/src/ReactFiberCommitWork.new.js
index c20719d8bfd96..3bf3940074228 100644
--- a/packages/react-reconciler/src/ReactFiberCommitWork.new.js
+++ b/packages/react-reconciler/src/ReactFiberCommitWork.new.js
@@ -35,6 +35,7 @@ import {
   enableSuspenseCallback,
   enableScopeAPI,
   enableStrictEffects,
+  deletedTreeCleanUpLevel,
 } from 'shared/ReactFeatureFlags';
 import {
   FunctionComponent,
@@ -60,6 +61,7 @@ import {
   hasCaughtError,
   clearCaughtError,
 } from 'shared/ReactErrorUtils';
+import {detachDeletedInstance} from './ReactFiberHostConfig';
 import {
   NoFlags,
   ContentReset,
@@ -1219,25 +1221,84 @@ function detachFiberMutation(fiber: Fiber) {
   // Don't reset the alternate yet, either. We need that so we can detach the
   // alternate's fields in the passive phase. Clearing the return pointer is
   // sufficient for findDOMNode semantics.
+  const alternate = fiber.alternate;
+  if (alternate !== null) {
+    alternate.return = null;
+  }
   fiber.return = null;
 }
 
-export function detachFiberAfterEffects(fiber: Fiber): void {
-  // Null out fields to improve GC for references that may be lingering (e.g. DevTools).
-  // Note that we already cleared the return pointer in detachFiberMutation().
-  fiber.alternate = null;
-  fiber.child = null;
-  fiber.deletions = null;
-  fiber.dependencies = null;
-  fiber.memoizedProps = null;
-  fiber.memoizedState = null;
-  fiber.pendingProps = null;
-  fiber.sibling = null;
-  fiber.stateNode = null;
-  fiber.updateQueue = null;
+function detachFiberAfterEffects(fiber: Fiber) {
+  const alternate = fiber.alternate;
+  if (alternate !== null) {
+    fiber.alternate = null;
+    detachFiberAfterEffects(alternate);
+  }
+
+  // Note: Defensively using negation instead of < in case
+  // `deletedTreeCleanUpLevel` is undefined.
+  if (!(deletedTreeCleanUpLevel >= 2)) {
+    // This is the default branch (level 0).
+    fiber.child = null;
+    fiber.deletions = null;
+    fiber.dependencies = null;
+    fiber.memoizedProps = null;
+    fiber.memoizedState = null;
+    fiber.pendingProps = null;
+    fiber.sibling = null;
+    fiber.stateNode = null;
+    fiber.updateQueue = null;
 
-  if (__DEV__) {
-    fiber._debugOwner = null;
+    if (__DEV__) {
+      fiber._debugOwner = null;
+    }
+  } else {
+    // Clear cyclical Fiber fields. This level alone is designed to roughly
+    // approximate the planned Fiber refactor. In that world, `setState` will be
+    // bound to a special "instance" object instead of a Fiber. The Instance
+    // object will not have any of these fields. It will only be connected to
+    // the fiber tree via a single link at the root. So if this level alone is
+    // sufficient to fix memory issues, that bodes well for our plans.
+    fiber.child = null;
+    fiber.deletions = null;
+    fiber.sibling = null;
+
+    // I'm intentionally not clearing the `return` field in this level. We
+    // already disconnect the `return` pointer at the root of the deleted
+    // subtree (in `detachFiberMutation`). Besides, `return` by itself is not
+    // cyclical — it's only cyclical when combined with `child`, `sibling`, and
+    // `alternate`. But we'll clear it in the next level anyway, just in case.
+
+    if (__DEV__) {
+      fiber._debugOwner = null;
+    }
+
+    if (deletedTreeCleanUpLevel >= 3) {
+      // Theoretically, nothing in here should be necessary, because we already
+      // disconnected the fiber from the tree. So even if something leaks this
+      // particular fiber, it won't leak anything else
+      //
+      // The purpose of this branch is to be super aggressive so we can measure
+      // if there's any difference in memory impact. If there is, that could
+      // indicate a React leak we don't know about.
+
+      // For host components, disconnect host instance -> fiber pointer.
+      if (fiber.tag === HostComponent) {
+        const hostInstance: Instance = fiber.stateNode;
+        if (hostInstance !== null) {
+          detachDeletedInstance(hostInstance);
+        }
+      }
+
+      fiber.return = null;
+      fiber.dependencies = null;
+      fiber.memoizedProps = null;
+      fiber.memoizedState = null;
+      fiber.pendingProps = null;
+      fiber.stateNode = null;
+      // TODO: Move to `commitPassiveUnmountInsideDeletedTreeOnFiber` instead.
+      fiber.updateQueue = null;
+    }
   }
 }
 
@@ -1629,11 +1690,8 @@ function commitDeletion(
       renderPriorityLevel,
     );
   }
-  const alternate = current.alternate;
+
   detachFiberMutation(current);
-  if (alternate !== null) {
-    detachFiberMutation(alternate);
-  }
 }
 
 function commitWork(current: Fiber | null, finishedWork: Fiber): void {
@@ -2308,14 +2366,34 @@ function commitPassiveUnmountEffects_begin() {
             fiberToDelete,
             fiber,
           );
+        }
 
-          // Now that passive effects have been processed, it's safe to detach lingering pointers.
-          const alternate = fiberToDelete.alternate;
-          detachFiberAfterEffects(fiberToDelete);
-          if (alternate !== null) {
-            detachFiberAfterEffects(alternate);
+        if (deletedTreeCleanUpLevel >= 1) {
+          // A fiber was deleted from this parent fiber, but it's still part of
+          // the previous (alternate) parent fiber's list of children. Because
+          // children are a linked list, an earlier sibling that's still alive
+          // will be connected to the deleted fiber via its `alternate`:
+          //
+          //   live fiber
+          //   --alternate--> previous live fiber
+          //   --sibling--> deleted fiber
+          //
+          // We can't disconnect `alternate` on nodes that haven't been deleted
+          // yet, but we can disconnect the `sibling` and `child` pointers.
+          const previousFiber = fiber.alternate;
+          if (previousFiber !== null) {
+            let detachedChild = previousFiber.child;
+            if (detachedChild !== null) {
+              previousFiber.child = null;
+              do {
+                const detachedSibling = detachedChild.sibling;
+                detachedChild.sibling = null;
+                detachedChild = detachedSibling;
+              } while (detachedChild !== null);
+            }
           }
         }
+
         nextEffect = fiber;
       }
     }
@@ -2392,7 +2470,8 @@ function commitPassiveUnmountEffectsInsideOfDeletedTree_begin(
     resetCurrentDebugFiberInDEV();
 
     const child = fiber.child;
-    // TODO: Only traverse subtree if it has a PassiveStatic flag
+    // TODO: Only traverse subtree if it has a PassiveStatic flag. (But, if we
+    // do this, still need to handle `deletedTreeCleanUpLevel` correctly.)
     if (child !== null) {
       ensureCorrectReturnPointer(child, fiber);
       nextEffect = child;
@@ -2409,19 +2488,35 @@ function commitPassiveUnmountEffectsInsideOfDeletedTree_complete(
 ) {
   while (nextEffect !== null) {
     const fiber = nextEffect;
-    if (fiber === deletedSubtreeRoot) {
-      nextEffect = null;
-      return;
+    const sibling = fiber.sibling;
+    const returnFiber = fiber.return;
+
+    if (deletedTreeCleanUpLevel >= 2) {
+      // Recursively traverse the entire deleted tree and clean up fiber fields.
+      // This is more aggressive than ideal, and the long term goal is to only
+      // have to detach the deleted tree at the root.
+      detachFiberAfterEffects(fiber);
+      if (fiber === deletedSubtreeRoot) {
+        nextEffect = null;
+        return;
+      }
+    } else {
+      // This is the default branch (level 0). We do not recursively clear all
+      // the fiber fields. Only the root of the deleted subtree.
+      if (fiber === deletedSubtreeRoot) {
+        detachFiberAfterEffects(fiber);
+        nextEffect = null;
+        return;
+      }
     }
 
-    const sibling = fiber.sibling;
     if (sibling !== null) {
-      ensureCorrectReturnPointer(sibling, fiber.return);
+      ensureCorrectReturnPointer(sibling, returnFiber);
       nextEffect = sibling;
       return;
     }
 
-    nextEffect = fiber.return;
+    nextEffect = returnFiber;
   }
 }
 
diff --git a/packages/react-reconciler/src/ReactFiberCommitWork.old.js b/packages/react-reconciler/src/ReactFiberCommitWork.old.js
index efdbc39abfdfc..7f4da55e76e2e 100644
--- a/packages/react-reconciler/src/ReactFiberCommitWork.old.js
+++ b/packages/react-reconciler/src/ReactFiberCommitWork.old.js
@@ -35,6 +35,7 @@ import {
   enableSuspenseCallback,
   enableScopeAPI,
   enableStrictEffects,
+  deletedTreeCleanUpLevel,
 } from 'shared/ReactFeatureFlags';
 import {
   FunctionComponent,
@@ -60,6 +61,7 @@ import {
   hasCaughtError,
   clearCaughtError,
 } from 'shared/ReactErrorUtils';
+import {detachDeletedInstance} from './ReactFiberHostConfig';
 import {
   NoFlags,
   ContentReset,
@@ -1219,25 +1221,84 @@ function detachFiberMutation(fiber: Fiber) {
   // Don't reset the alternate yet, either. We need that so we can detach the
   // alternate's fields in the passive phase. Clearing the return pointer is
   // sufficient for findDOMNode semantics.
+  const alternate = fiber.alternate;
+  if (alternate !== null) {
+    alternate.return = null;
+  }
   fiber.return = null;
 }
 
-export function detachFiberAfterEffects(fiber: Fiber): void {
-  // Null out fields to improve GC for references that may be lingering (e.g. DevTools).
-  // Note that we already cleared the return pointer in detachFiberMutation().
-  fiber.alternate = null;
-  fiber.child = null;
-  fiber.deletions = null;
-  fiber.dependencies = null;
-  fiber.memoizedProps = null;
-  fiber.memoizedState = null;
-  fiber.pendingProps = null;
-  fiber.sibling = null;
-  fiber.stateNode = null;
-  fiber.updateQueue = null;
+function detachFiberAfterEffects(fiber: Fiber) {
+  const alternate = fiber.alternate;
+  if (alternate !== null) {
+    fiber.alternate = null;
+    detachFiberAfterEffects(alternate);
+  }
+
+  // Note: Defensively using negation instead of < in case
+  // `deletedTreeCleanUpLevel` is undefined.
+  if (!(deletedTreeCleanUpLevel >= 2)) {
+    // This is the default branch (level 0).
+    fiber.child = null;
+    fiber.deletions = null;
+    fiber.dependencies = null;
+    fiber.memoizedProps = null;
+    fiber.memoizedState = null;
+    fiber.pendingProps = null;
+    fiber.sibling = null;
+    fiber.stateNode = null;
+    fiber.updateQueue = null;
 
-  if (__DEV__) {
-    fiber._debugOwner = null;
+    if (__DEV__) {
+      fiber._debugOwner = null;
+    }
+  } else {
+    // Clear cyclical Fiber fields. This level alone is designed to roughly
+    // approximate the planned Fiber refactor. In that world, `setState` will be
+    // bound to a special "instance" object instead of a Fiber. The Instance
+    // object will not have any of these fields. It will only be connected to
+    // the fiber tree via a single link at the root. So if this level alone is
+    // sufficient to fix memory issues, that bodes well for our plans.
+    fiber.child = null;
+    fiber.deletions = null;
+    fiber.sibling = null;
+
+    // I'm intentionally not clearing the `return` field in this level. We
+    // already disconnect the `return` pointer at the root of the deleted
+    // subtree (in `detachFiberMutation`). Besides, `return` by itself is not
+    // cyclical — it's only cyclical when combined with `child`, `sibling`, and
+    // `alternate`. But we'll clear it in the next level anyway, just in case.
+
+    if (__DEV__) {
+      fiber._debugOwner = null;
+    }
+
+    if (deletedTreeCleanUpLevel >= 3) {
+      // Theoretically, nothing in here should be necessary, because we already
+      // disconnected the fiber from the tree. So even if something leaks this
+      // particular fiber, it won't leak anything else
+      //
+      // The purpose of this branch is to be super aggressive so we can measure
+      // if there's any difference in memory impact. If there is, that could
+      // indicate a React leak we don't know about.
+
+      // For host components, disconnect host instance -> fiber pointer.
+      if (fiber.tag === HostComponent) {
+        const hostInstance: Instance = fiber.stateNode;
+        if (hostInstance !== null) {
+          detachDeletedInstance(hostInstance);
+        }
+      }
+
+      fiber.return = null;
+      fiber.dependencies = null;
+      fiber.memoizedProps = null;
+      fiber.memoizedState = null;
+      fiber.pendingProps = null;
+      fiber.stateNode = null;
+      // TODO: Move to `commitPassiveUnmountInsideDeletedTreeOnFiber` instead.
+      fiber.updateQueue = null;
+    }
   }
 }
 
@@ -1629,11 +1690,8 @@ function commitDeletion(
       renderPriorityLevel,
     );
   }
-  const alternate = current.alternate;
+
   detachFiberMutation(current);
-  if (alternate !== null) {
-    detachFiberMutation(alternate);
-  }
 }
 
 function commitWork(current: Fiber | null, finishedWork: Fiber): void {
@@ -2308,14 +2366,34 @@ function commitPassiveUnmountEffects_begin() {
             fiberToDelete,
             fiber,
           );
+        }
 
-          // Now that passive effects have been processed, it's safe to detach lingering pointers.
-          const alternate = fiberToDelete.alternate;
-          detachFiberAfterEffects(fiberToDelete);
-          if (alternate !== null) {
-            detachFiberAfterEffects(alternate);
+        if (deletedTreeCleanUpLevel >= 1) {
+          // A fiber was deleted from this parent fiber, but it's still part of
+          // the previous (alternate) parent fiber's list of children. Because
+          // children are a linked list, an earlier sibling that's still alive
+          // will be connected to the deleted fiber via its `alternate`:
+          //
+          //   live fiber
+          //   --alternate--> previous live fiber
+          //   --sibling--> deleted fiber
+          //
+          // We can't disconnect `alternate` on nodes that haven't been deleted
+          // yet, but we can disconnect the `sibling` and `child` pointers.
+          const previousFiber = fiber.alternate;
+          if (previousFiber !== null) {
+            let detachedChild = previousFiber.child;
+            if (detachedChild !== null) {
+              previousFiber.child = null;
+              do {
+                const detachedSibling = detachedChild.sibling;
+                detachedChild.sibling = null;
+                detachedChild = detachedSibling;
+              } while (detachedChild !== null);
+            }
           }
         }
+
         nextEffect = fiber;
       }
     }
@@ -2392,7 +2470,8 @@ function commitPassiveUnmountEffectsInsideOfDeletedTree_begin(
     resetCurrentDebugFiberInDEV();
 
     const child = fiber.child;
-    // TODO: Only traverse subtree if it has a PassiveStatic flag
+    // TODO: Only traverse subtree if it has a PassiveStatic flag. (But, if we
+    // do this, still need to handle `deletedTreeCleanUpLevel` correctly.)
     if (child !== null) {
       ensureCorrectReturnPointer(child, fiber);
       nextEffect = child;
@@ -2409,19 +2488,35 @@ function commitPassiveUnmountEffectsInsideOfDeletedTree_complete(
 ) {
   while (nextEffect !== null) {
     const fiber = nextEffect;
-    if (fiber === deletedSubtreeRoot) {
-      nextEffect = null;
-      return;
+    const sibling = fiber.sibling;
+    const returnFiber = fiber.return;
+
+    if (deletedTreeCleanUpLevel >= 2) {
+      // Recursively traverse the entire deleted tree and clean up fiber fields.
+      // This is more aggressive than ideal, and the long term goal is to only
+      // have to detach the deleted tree at the root.
+      detachFiberAfterEffects(fiber);
+      if (fiber === deletedSubtreeRoot) {
+        nextEffect = null;
+        return;
+      }
+    } else {
+      // This is the default branch (level 0). We do not recursively clear all
+      // the fiber fields. Only the root of the deleted subtree.
+      if (fiber === deletedSubtreeRoot) {
+        detachFiberAfterEffects(fiber);
+        nextEffect = null;
+        return;
+      }
     }
 
-    const sibling = fiber.sibling;
     if (sibling !== null) {
-      ensureCorrectReturnPointer(sibling, fiber.return);
+      ensureCorrectReturnPointer(sibling, returnFiber);
       nextEffect = sibling;
       return;
     }
 
-    nextEffect = fiber.return;
+    nextEffect = returnFiber;
   }
 }
 
diff --git a/packages/react-reconciler/src/forks/ReactFiberHostConfig.custom.js b/packages/react-reconciler/src/forks/ReactFiberHostConfig.custom.js
index 5bfdf3a305f32..6a6e9c5e040c3 100644
--- a/packages/react-reconciler/src/forks/ReactFiberHostConfig.custom.js
+++ b/packages/react-reconciler/src/forks/ReactFiberHostConfig.custom.js
@@ -73,6 +73,7 @@ export const preparePortalMount = $$$hostConfig.preparePortalMount;
 export const prepareScopeUpdate = $$$hostConfig.preparePortalMount;
 export const getInstanceFromScope = $$$hostConfig.getInstanceFromScope;
 export const getCurrentEventPriority = $$$hostConfig.getCurrentEventPriority;
+export const detachDeletedInstance = $$$hostConfig.detachDeletedInstance;
 
 // -------------------
 //      Microtasks
diff --git a/packages/react-test-renderer/src/ReactTestHostConfig.js b/packages/react-test-renderer/src/ReactTestHostConfig.js
index a787d31840af3..bac900c469fa7 100644
--- a/packages/react-test-renderer/src/ReactTestHostConfig.js
+++ b/packages/react-test-renderer/src/ReactTestHostConfig.js
@@ -360,3 +360,7 @@ export function prepareScopeUpdate(scopeInstance: Object, inst: Object): void {
 export function getInstanceFromScope(scopeInstance: Object): null | Object {
   return nodeToInstanceMap.get(scopeInstance) || null;
 }
+
+export function detachDeletedInstance(node: Instance): void {
+  // noop
+}
diff --git a/packages/shared/ReactFeatureFlags.js b/packages/shared/ReactFeatureFlags.js
index 77079bba3a6a1..a1e9c42d3d1c8 100644
--- a/packages/shared/ReactFeatureFlags.js
+++ b/packages/shared/ReactFeatureFlags.js
@@ -112,6 +112,19 @@ export const disableNativeComponentFrames = false;
 // If there are no still-mounted boundaries, the errors should be rethrown.
 export const skipUnmountedBoundaries = false;
 
+// When a node is unmounted, recurse into the Fiber subtree and clean out
+// references. Each level cleans up more fiber fields than the previous level.
+// As far as we know, React itself doesn't leak, but because the Fiber contains
+// cycles, even a single leak in product code can cause us to retain large
+// amounts of memory.
+//
+// The long term plan is to remove the cycles, but in the meantime, we clear
+// additional fields to mitigate.
+//
+// It's an enum so that we can experiment with different levels of
+// aggressiveness.
+export const deletedTreeCleanUpLevel = 1;
+
 // --------------------------
 // Future APIs to be deprecated
 // --------------------------
diff --git a/packages/shared/forks/ReactFeatureFlags.native-fb.js b/packages/shared/forks/ReactFeatureFlags.native-fb.js
index 2e2f64e4bc5d0..7d5c5a6c40cc4 100644
--- a/packages/shared/forks/ReactFeatureFlags.native-fb.js
+++ b/packages/shared/forks/ReactFeatureFlags.native-fb.js
@@ -46,6 +46,7 @@ export const enableLegacyFBSupport = false;
 export const enableFilterEmptyStringAttributesDOM = false;
 export const disableNativeComponentFrames = false;
 export const skipUnmountedBoundaries = false;
+export const deletedTreeCleanUpLevel = 1;
 
 export const enableNewReconciler = false;
 export const deferRenderPhaseUpdateToNextBatch = true;
diff --git a/packages/shared/forks/ReactFeatureFlags.native-oss.js b/packages/shared/forks/ReactFeatureFlags.native-oss.js
index 34ee7d2b7a843..cd2979fc400f9 100644
--- a/packages/shared/forks/ReactFeatureFlags.native-oss.js
+++ b/packages/shared/forks/ReactFeatureFlags.native-oss.js
@@ -45,6 +45,7 @@ export const enableLegacyFBSupport = false;
 export const enableFilterEmptyStringAttributesDOM = false;
 export const disableNativeComponentFrames = false;
 export const skipUnmountedBoundaries = false;
+export const deletedTreeCleanUpLevel = 1;
 
 export const enableNewReconciler = false;
 export const deferRenderPhaseUpdateToNextBatch = true;
diff --git a/packages/shared/forks/ReactFeatureFlags.test-renderer.js b/packages/shared/forks/ReactFeatureFlags.test-renderer.js
index bd5e91885ca44..c7f1f1a4739d4 100644
--- a/packages/shared/forks/ReactFeatureFlags.test-renderer.js
+++ b/packages/shared/forks/ReactFeatureFlags.test-renderer.js
@@ -45,6 +45,7 @@ export const enableLegacyFBSupport = false;
 export const enableFilterEmptyStringAttributesDOM = false;
 export const disableNativeComponentFrames = false;
 export const skipUnmountedBoundaries = false;
+export const deletedTreeCleanUpLevel = 1;
 
 export const enableNewReconciler = false;
 export const deferRenderPhaseUpdateToNextBatch = true;
diff --git a/packages/shared/forks/ReactFeatureFlags.test-renderer.native.js b/packages/shared/forks/ReactFeatureFlags.test-renderer.native.js
index 70c5dc4144ee8..895ebad1d809e 100644
--- a/packages/shared/forks/ReactFeatureFlags.test-renderer.native.js
+++ b/packages/shared/forks/ReactFeatureFlags.test-renderer.native.js
@@ -45,6 +45,7 @@ export const enableLegacyFBSupport = false;
 export const enableFilterEmptyStringAttributesDOM = false;
 export const disableNativeComponentFrames = false;
 export const skipUnmountedBoundaries = false;
+export const deletedTreeCleanUpLevel = 1;
 
 export const enableNewReconciler = false;
 export const deferRenderPhaseUpdateToNextBatch = true;
diff --git a/packages/shared/forks/ReactFeatureFlags.test-renderer.www.js b/packages/shared/forks/ReactFeatureFlags.test-renderer.www.js
index df6bbdf03fbed..832f56e6fa093 100644
--- a/packages/shared/forks/ReactFeatureFlags.test-renderer.www.js
+++ b/packages/shared/forks/ReactFeatureFlags.test-renderer.www.js
@@ -45,6 +45,7 @@ export const enableLegacyFBSupport = false;
 export const enableFilterEmptyStringAttributesDOM = false;
 export const disableNativeComponentFrames = false;
 export const skipUnmountedBoundaries = false;
+export const deletedTreeCleanUpLevel = 1;
 
 export const enableNewReconciler = false;
 export const deferRenderPhaseUpdateToNextBatch = true;
diff --git a/packages/shared/forks/ReactFeatureFlags.testing.js b/packages/shared/forks/ReactFeatureFlags.testing.js
index 42003be9a388b..351b0934c7924 100644
--- a/packages/shared/forks/ReactFeatureFlags.testing.js
+++ b/packages/shared/forks/ReactFeatureFlags.testing.js
@@ -45,6 +45,7 @@ export const enableLegacyFBSupport = false;
 export const enableFilterEmptyStringAttributesDOM = false;
 export const disableNativeComponentFrames = false;
 export const skipUnmountedBoundaries = false;
+export const deletedTreeCleanUpLevel = 1;
 
 export const enableNewReconciler = false;
 export const deferRenderPhaseUpdateToNextBatch = true;
diff --git a/packages/shared/forks/ReactFeatureFlags.testing.www.js b/packages/shared/forks/ReactFeatureFlags.testing.www.js
index 5ab680976a9e4..b25ac0073e944 100644
--- a/packages/shared/forks/ReactFeatureFlags.testing.www.js
+++ b/packages/shared/forks/ReactFeatureFlags.testing.www.js
@@ -45,6 +45,7 @@ export const enableLegacyFBSupport = !__EXPERIMENTAL__;
 export const enableFilterEmptyStringAttributesDOM = false;
 export const disableNativeComponentFrames = false;
 export const skipUnmountedBoundaries = true;
+export const deletedTreeCleanUpLevel = 1;
 
 export const enableNewReconciler = false;
 export const deferRenderPhaseUpdateToNextBatch = true;
diff --git a/packages/shared/forks/ReactFeatureFlags.www-dynamic.js b/packages/shared/forks/ReactFeatureFlags.www-dynamic.js
index e2496510ef24c..503d263fc9be6 100644
--- a/packages/shared/forks/ReactFeatureFlags.www-dynamic.js
+++ b/packages/shared/forks/ReactFeatureFlags.www-dynamic.js
@@ -52,6 +52,7 @@ export const disableNativeComponentFrames = false;
 export const createRootStrictEffectsByDefault = false;
 export const enableStrictEffects = false;
 export const enableUseRefAccessWarning = __VARIANT__;
+export const deletedTreeCleanUpLevel = __VARIANT__ ? 3 : 1;
 
 export const enableProfilerNestedUpdateScheduledHook = __VARIANT__;
 export const disableSchedulerTimeoutInWorkLoop = __VARIANT__;
diff --git a/packages/shared/forks/ReactFeatureFlags.www.js b/packages/shared/forks/ReactFeatureFlags.www.js
index c29856558751e..dab1a37bc5c69 100644
--- a/packages/shared/forks/ReactFeatureFlags.www.js
+++ b/packages/shared/forks/ReactFeatureFlags.www.js
@@ -32,6 +32,7 @@ export const {
   disableNativeComponentFrames,
   disableSchedulerTimeoutInWorkLoop,
   enableLazyContextPropagation,
+  deletedTreeCleanUpLevel,
 } = dynamicFeatureFlags;
 
 // On WWW, __EXPERIMENTAL__ is used for a new modern build.