1. Ever since teens had access to social media, there have been studies on the matter, (i'll admit, that in early years they were pretty scandalous, but now they try to act as more of a guide or recommendation for parents).

Here you got one source (again, of many):

https://www.sydney.edu.au/arts/news-and-events/news/2023/10/06/new-study-reveals-teenagers-social-media-use-and-safety-concerns.html

2. The Fediverse is mostly handled by moderators and the community (like Reddit used to be), so when there's an issue regarding ill behaviour, it is usually handled inside that community. (And besides, instances have their own rules too.)

3. It's toxic waste, get the hell out of there. 💀☢️