User Agent: Mozilla/5.0 (Windows NT 6.1; rv:60.0) Gecko/20100101 Firefox/60.0

Steps to reproduce:

One this page:

https://www.ebay.com/itm/254271103732

NOTE 1: Tried in the regular mode (Modern theme, add-ons enabled etc)
and in the safe mode. The crash happens in both cases. I am using
SeaMonkey 2.53.5.1 32-bit on Windows 7 32-bit.

NOTE 2: There were multiple back-to-back crashes since I was trying to narrow
down the root cause. All crash dumps are submitted through the crash reporter.

Actual results:

SeaMonkey crashes with 100% probability

Expected results:

The page should be opened

NOT reproducible with installed unofficial (by wg9s) De SeaMonkey 2.53.6 beta 1 pre Mozilla/5.0 (NT 6.1; Win64; x64; rv:60.0) Gecko/20100101 Firefox/60.0 Build 20201115220004 (My default User Profile, Default Classic Theme) on German WIN7 64bit

https://crash-stats.mozilla.org/report/index/9d1311ee-c0af-4bd6-97c5-46dba0201202
Stack overflow in the 32 bit version only. 2.53.6b1 pre msvc builds are also affected.

Does not happen with Bills clang 9 2.53.6 beta 1 pre build. Can be used as a workaround https://www.wg9s.com/comm-253/

Will be fixed in 2.53.6 by either switching compilers or deactivating av1 or simd support. I think it is caused by one of the two new options.

Fixed by switching to clang 11 for Windows x86 in 2.53.6b1.