There have been a number of comment spam attacks in various posts in a couple of /c's that I follow by a user/individual who uses account names like Thulean*

For example: ThuleanSneed@lemmy.tf in !coffee@lemmy.world

and ThuleanPerspective2@eviltoast.org in !anime@ani.social

edit: Also ThuleanSneed@startrek.website in !startrek@startrek.website

The posts have been removed or deleted by the respective /c's mods, and the offending accounts banned, but you can see the traces of them in those /c's modlogs.

The comments consist of an all-caps string of words with profanities, and Simpsons memes.

An attack on a post may consist of several repeated or similar looking comments.

This looks like a bored teenager prank, but it may also be an organization testing Lemmy's systemic and collective defenses and ability to respond against spam and bot posts.