it’s open-source and de-centralized as well, which omits censorship

Not necessarily. It simply allows people to leave an instance that is applying censorship. Admins and mods on instances can essentially do whatever they want. The fediverse could have the same problems the big tech sites do. If most people congregate to single, popular instances of the fediverse, that instance essentially becomes a non-distributed social media site. Then all they have to do is start de-federating and start imposing their own restrictive rules and we're right back to where we started.

It's exactly what everyone is scared of with Threads coming into the Fediverse. If they, or another big instance, sucks most users into their instance they effectively can neuter the fediverse. In order to prevent this, all users need to be aware of moderation on their instances and draconian moderation on other instances. We need to be aware of de-federation for instances to spot those trying to isolate themselves as a way to control their users (instead of self-preservation).