The biggest problem with “federation” is the control given to bullshit admins in some of the biggest and how big into hiding their problems they are. One of the biggest instances has shoved two of their admins under the rug, without openly acknowledging why they did it or the drama there clearly is behind it, giving the impression that the problems those admins were creating have been addressed on one side and on the other just trying to dismiss it as “no big deal, they are just taking time off”.
So keep in mind joining some of those instances is just joining a good paint job. Sometimes, the rust breaks through, sometimes the rusted pieces get removed, but the people painting over the rust are still there.
It matters because when communities crowd around large instances, those admins have ultimate control over participation within them. And while easy to bypass, it will still affect the reputation your comment history would have represented.
Any social networks that have non-censored participants are. Usually, China’s presence in social networks outside of its borders are for propaganda purposes.