Out of curiosity, I looked at what I was banned from: some of them are communities I’ve never even interacted with like !tesseract@dubvee.org? What is that even?
And slrpnk has an automated bot now that bans and unbans people. Again, from a community I don’t even recognize (pleasant politics? huh?).
That seems quite easy to game. Create a bunch of accounts across multiple instances, target a user you don’t like, find comments / posts with low vote counts and downvote all of those. That’ll skew the ratio and get them “preemtively” banned from communities that use that bot.