The "kind" of event that clients use to store the list of communities you've joined is changing.
Currently its stored as a kind:30001 with a name of "communities" although this ends up just cluttering up other list views.
Instead its getting its own kind:10004 which should make things a little cleaner from the clients point of view.

Q. How dose this effect the communities I've joined?
It wont effect anything, at least for noStrudel. Although for a little while the communities you've joined might be out of sync with other clients. at least until they update to use the new event kind

Q. How do I migrate my list of communities?
Joining or leaving a community in noStrudel will automatically migrate your communities list. so maybe join my community? nostr:naddr1qqykum6nw3e82er9dsqs6amnwvaz7tmwdaejumr0dsq3qamnwvaz7tmwdaehgu3wwa5kuegzyqnxs90qeyssm73jf3kt5dtnk997ujw6ggy6j3t0jjzw2yrv6sy22qcyqqqgdasgrw3py