Maybe? "Identity-based activist communities" are incredibly toxic as a rule.

Maybe there's lasting harm from engaging in them early. Or maybe it's better to get exposed to them early in your life, so that you have time to figure out why you don't want anything to do with them.

Either way, it seems pretty clear that preventing children and teens from engaging them is a nonstarter. You can't get anywhere close to consensus on "this is harmful and should be banned" because, guess what, someone's entire identity is going to be built around such communities.