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!
Yeah, I don’t contribute, but I do read them daily. And being banned actually removes them from your sidebar of “subscribed” communities. That’s how I noticed.
I wouldn’t care if I deserved it. But I really didn’t do anything.