Predator and CL did not provide any possible suspects.
Using Code Search for the file, "PaintLayerScrollableArea.h" assigning to concern owner.

Suspecting Commit#
https://chromium.googlesource.com/chromium/src/+/8971f74f9977918237228a5c78e5a09e77799e0d

@szager -- 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 495551:495853.

Detailed report: https://clusterfuzz.com/testcase?key=4678929079336960

Fuzzer: ifratric-browserfuzzer-v3
Job Type: windows_asan_chrome
Platform Id: windows

Crash Type: Null-dereference READ
Crash Address: 0x000000bc
Crash State:
  blink::PaintLayerScrollableArea::EnsureRareData
  blink::LocalFrameView::UpdateLayersAndCompositingAfterScrollIfNeeded
  blink::LocalFrameView::UpdateScrollOffset
  
Sanitizer: address (ASAN)

Regressed: https://clusterfuzz.com/revisions?job=windows_asan_chrome&range=487225:487317
Fixed: https://clusterfuzz.com/revisions?job=windows_asan_chrome&range=495551:495853

Reproducer Testcase: https://clusterfuzz.com/download?testcase_id=4678929079336960

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 4678929079336960 is verified as fixed, so closing issue as verified.

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