Predator and CL could not provide any possible suspects.
Using Code Search for the file, "axobjectcacheimpl.cpp" assigning to concern owner.

Suspecting Commit#
https://chromium.googlesource.com/chromium/src/+/1b5b587f547319a4dc72d06fc25b0494826fd9cd

@nverne -- Could you please look into the issue, kindly re-assign if this is not related to your changes.
Thank You.

ClusterFuzz has detected this issue as fixed in range 499699:499749.

Detailed report: https://clusterfuzz.com/testcase?key=5062877781426176

Fuzzer: inferno_layout_test_unmodified
Job Type: windows_syzyasan_content_shell
Platform Id: windows

Crash Type: Null-dereference
Crash Address: 0x0000004f
Crash State:
  WTF::HashTable<blink::Member<blink::MessagePort>,blink::Member<blink::MessagePor
  blink::AXObjectCacheImpl::GenerateAXID
  blink::AXObjectCacheImpl::GetOrCreateAXID
  
Memory Tool: SYZYASAN

Regressed: https://clusterfuzz.com/revisions?job=windows_syzyasan_content_shell&range=483471:483525
Fixed: https://clusterfuzz.com/revisions?job=windows_syzyasan_content_shell&range=499699:499749

Reproducer Testcase: https://clusterfuzz.com/download?testcase_id=5062877781426176

See https://github.com/google/clusterfuzz-tools for more information.

If you suspect that the result above is incorrect, try re-doing that job on the test case report page.

ClusterFuzz testcase 5062877781426176 is verified as fixed, so closing issue as verified.

If this is incorrect, please add ClusterFuzz-Wrong label and re-open the issue.