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

Suspecting Commit#
https://chromium.googlesource.com/chromium/src/+/c37a2a46dbb2b98e9b35cb5de0c03502c075c6d6

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

Change to Untriaged to get team member's attention.

Lower to Pri-3 since real world usage of InsertList command is low.

ClusterFuzz has detected this issue as fixed in range 526278:526279.

Detailed report: https://clusterfuzz.com/testcase?key=5901637817466880

Job Type: linux_debug_content_shell_drt
Crash Type: CHECK failure
Crash Address: 
Crash State:
  next_list_child != list_child_node (DD(editable)) in InsertListCommand.cpp
  blink::InsertListCommand::UnlistifyParagraph
  blink::InsertListCommand::DoApplyForSingleParagraph
  
Sanitizer: address (ASAN)

Regressed: https://clusterfuzz.com/revisions?job=linux_debug_content_shell_drt&range=283188:283414
Fixed: https://clusterfuzz.com/revisions?job=linux_debug_content_shell_drt&range=526278:526279

Reproducer Testcase: https://clusterfuzz.com/download?testcase_id=5901637817466880

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 5901637817466880 is verified as fixed, so closing issue as verified.

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