satellite.earth and nostrudel.ninjas do communities to a somewhat bearable level, they'll get better. A month ago nostrudel wasn't really a thing at all, for example.
Curious - how do they make a community on Nostr? Is it just a relay?
Relays just carry notes, clients need to interpret those notes so that they make sense. satellite.earth and nostrudel.ninja have additional smarts to assign notes to communities etc, other clients just show them as normal notes and don't feature communities at all. Relays don't really play a part in it, they just carry data. Clients are the ones that make sense of it. You can think of relays as being a distributed database.