Regarding Federation … The web, email, Usenet, the internet itself, these are/were all federated platforms. They are also all open and always have issues with bad actors.
The other side of it, it is all a work in progress especially lemmy. So it is all half baked in that sense. Especially in the case of bad actors, there are known things to address but no solutions. People do not even agree in what a bad actor is until things get extreme.