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

Suspecting Commit#
https://chromium.googlesource.com/chromium/src/+/d060c2003fffcfec35db5789ce708340f46c181a

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

ClusterFuzz testcase 4792322241069056 is flaky and no longer reproduces, so closing issue.

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