Due to some unlucky coincidences, I saw the lemmy release notes 21 minutes after it was released.
Recently some malicious users started to use an exploit where they would post rule violating content and then delete the account. This would prevent admins and mods from viewing the user profile to find other posts, and would also prevent federation of ban actions.
If people are curious if one can just delete an actor in the W3C ActivityPub context. Well no.
I have not investigated the details.