I have been permanently banned for staying on topic!?

Reddit makes perfect sense: having you there is no longer profitable.

Fuck them to be honest..

Damn, they are probably going to ban me next

Considering the sub in question is /r/redditalternatives, you posted this in a thread about alternative communities on lemmy, and there's a reply to your comment which promotes more lemmy (and mbin) instances that isn't removed... I really really doubt the reason for the ban was you mentioning Lemmy. That would be very inconsistent of the mods, and actually suggest a vendetta against you personally rather than lemmy.

Did you reply to the message asking what rule you broke? Like the ban message instructs you to? Might have also been an accidential ban.

It did not violate any community rules. Reddit doesn't make any sense.

Sadly, sidebar rules on Old Reddit aren't real and so can't be relied upon. There are in fact more than just four rules. There's nine of them.

That said, even with the expanded list of rules I can't find any that might apply. Unless their automoderator is so heavily sensitive to non-civility that the very word "cuss" is seen as bad language. Which I very much doubt. It does mention that linking to websites containing malware leads to an immediate permaban, but I doubt that's the case here?

You broke rule 1. You didn't include an elevator pitch.