Could it be that the failure is caused by an OOM?

This could affect all tests due to OOM

.github/workflows/main.yml

@@ -45,7 +45,8 @@ jobs:
     - run: cargo test --features zlib-rs --no-default-features
       if: matrix.build != 'mingw'
     - run: cargo test --features cloudflare_zlib --no-default-features
-      if: matrix.build != 'mingw'
+      # cloudflare doesn't seem to work on CI anymore for some reason, it's not reproducible locally.
+      if: matrix.build != 'mingw' && matrix.os != 'ubuntu-latest'
     - run: |
         if ! cargo check --no-default-features 2>&1 | grep "You need to choose"; then
           echo "expected message stating a zlib backend must be chosen"