A while back I signed up to rammy.site a small lemmy instance run by a single person. It was a very nice instance, very stable and had pretty good access to other instances, or at least it used to. Recently though all of that has changed when the instance was taken over by far right-wing users from the right-wing instance known as exploding-heads, an instance which has been blocked by many others for the hateful content they post and the abusive behavior of its members. The reason that this was even allowed to happen was that the admin stopped moderating the server but left the server online, this is a problem because it means that anyone can hop onto the server and start posting whatever they want and create whatever communities they want and no-one can stop them.
There isn’t much you can do to prevent going innactive but there are ways to mitigate what happened on rammy.site to prevent a full blown catastrophe like what has happened here. If you run a server and you are going to be going away for a while I’d recommend turning off account registration and community creation on your instance, that wouldn’t prevent federated users and existing users from spamming existing communities but it would help against users joining the site and creating new communities which is what happened here on rammy.
I understand that it’s not always possible to always be there to moderate your instance but you can at lease take steps to ensure that in your absence the instance won’t be utterly decimated and/or used as a weapon to spread hatred or attack other instances.
Admins of instances have a “purge user” button (or is that only for communities?) where you can basically defederate a single user or community.
The purge button appears when you ban a user.
It takes a lot of CPU and I/O to purge a user, though. Not really feasible when you’re banning groups.
There is also a “purge community” button. But I have learned that if I purge a non-local community the purge is so complete that your instamce forgets it ever existed… And it can simply be fetched again!