This particular community was removed this morning (as you can see in the modlog).

I don’t want to go into too many details, but suffice it to say that this is not the first time the responsible users (or, potentially, single user with multiple accounts) has tried to cause disruptions on lemm.ee, so this is why they have been banned from lemm.ee as well.

I know the community is still visible on sh.itjust.works. The reason for this is most likely technical - either the community removal action did not get received properly by that instance, or the fact that one of the mods was a user of that instance has prevented the removal from being acknowledged by sh.itjust.works. Either way, lemm.ee is not hosting this community anymore.