Not that this makes any of the other answers wrong, but the actual answer is that it was probably a 30-day temporary instance ban.

When a remote account is instance banned, it's automatically banned from any communities on the instance it has interacted with and uses the same expiration date and reason as the instance ban. Lemmy does that automatically in the backend.

If you're viewing the modlog from another instance, however, you don't see the instance ban (only the community bans federate) so it makes it appear the mod is having a hissy fit.

Again, and given the instance involved, this does not mean any of the other answers are wrong, lol, just incomplete.

When this happens it's always Dessalines trying to merge new code instead of spending all his time governing his fiefdom.

It’s from the .ml Nazis that simp Ai and slurp fascist cock.

Just block that whole instance and avoid the shitheads altogether.