Predator and CL could not provide any possible suspects.
Using Code Search for the file, "layoutview.cpp" assigning to the concern owner who might be related.

Suspecting Commit#
https://chromium.googlesource.com/chromium/src/+/1fac40c94ca96fc8bac2b00aab7bddc0d3a7b851

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

The clusterfuzz report provides a regression range. The "suspected commit" is not in that range.

Perhaps it's https://chromium.googlesource.com/chromium/src/+/bbcefe73280faa1c5b52349df11f45906ce14d44 which is in the range.

ClusterFuzz has detected this issue as fixed in range 500805:500806.

Detailed report: https://clusterfuzz.com/testcase?key=5665167756230656

Fuzzer: bj_broddelwerk
Job Type: windows_syzyasan_chrome
Platform Id: windows

Crash Type: Null-dereference
Crash Address: 0x00000008
Crash State:
  blink::CalcSelectionRangeAndSetSelectionState
  blink::LayoutSelection::Commit
  blink::LayoutView::CommitPendingSelection
  
Memory Tool: SYZYASAN

Regressed: https://clusterfuzz.com/revisions?job=windows_syzyasan_chrome&range=496861:496900
Fixed: https://clusterfuzz.com/revisions?job=windows_syzyasan_chrome&range=500805:500806

Reproducer Testcase: https://clusterfuzz.com/download?testcase_id=5665167756230656

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.