A couple fandom communities:
This is an excellent point that I thought about when a previous community I was active in got shut down on the ml instance due to some admin whims. Since then, for the two communities I run, I have an external wiki that I maintain with things like complete rules or an index of past weekly discussion threads, etc. These wikis are set up on a VPS that I am responsible for, independent of the host instance of my communities.
ani.social and the admin, @[email protected], has been excellent, and the instance is a logical place for anime/manga communities. I have also tried to keep up donations to keep the server running, but people’s lives change, not always by choice. Having some form of communication independent of the lemmy instance makes sense for those scenarios, if for nothing else except for communicating a migration to a different instance.
A lot of the anime-related communities have consolidated over time to the ani.social instance. There are historical reasons for this (largely due to hostility from the ml admins), and if you want a brief history for just the general anime community, I previously wrote a post here.
That being said, the ani.social instance has been growing with new communities being added. Here are the more active ones:
General Communities
Series-Specific Communities
Misc.