Write something that describes what federation is (apparently everyone is scared by this word)
I keep writing some variant of
Federated does not mean that your data is spread across a bunch of servers automatically. Federated means you have the option to talk to people on other servers. So yes the room is federated (unless you disabled it on the room) but that doesn't mean I can see your chat or something. A private room is a private room. If the only people in the room are on your server, your data doesn't go to any other server.