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.
A lot of this stems from instances running old versions with loose registration requirements, like no captcha. This is a problem in a federated system because there’s no barrier for a banned user to just jump to another instance.
Perhaps it would be a good idea if, when Lemmy has anti-spam measures implemented like rate-limiting and captchas for registration, it disabled federation with instances that are at a lower version, to motivate small instances to upgrade and enable the new features.