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.
This wouldn't really solve the issue as the user could rather simply create as many accounts as they like to circumvent per-account limits.