Nah, it just takes one user to get a community onto an instance’s All feed. After that, frequency and position are (mostly) based on the posts’ overall popularity. It’s more complicated than just that, but I don’t really understand how federation is incorporated in that.
And to put it in perspective, lemm.ee and startrek.website combined user total is <10k. sh.itjust.works has 28k and lemmy.world has 138k. Bound to be more diversity with numbers like that.
16 October 2023 (sh.itjust.works)