I really have no idea why I was banned from those two communities specifically. I don’t think I’ve interacted with any of them (apart from reading/voting) for weeks. It’s not an instance ban.
If there is a better place to post this, please tell me.
EDIT:
I posted a link that was falsely flagged as malicious, have been unbanned! See comments for more details!
It does say “automod” so I think it might just be a mistake. But I contacted a couple of mods, maybe somebody can fix it (or explain it). I’ll update the post if that happens.