> PG Bug reporting form <noreply(at)postgresql(dot)org> writes:
>> This looks to me like a low level issue with Postgres13 and TOAST objects of
>> a specific size and or compression behavior.
After looking at it some more, I'm pretty sure that these issues could
explain your problem, though it's possible there's an additional
contributing issue. If you're in a position to apply a patch and
see whether it fixes the problem, please try
https://git.postgresql.org/gitweb/?p=postgresql.git;a=patch;h=2330f4d3a87ac43b6ecd31bfd698384888ed03cb
regards, tom lane