Full URL links to communities appear to open fine - even if the instance isn’t aware of that community (hurray! thank you for this, it’s ace!)
However, links with exclamation marks seem to try to open a user.
I’m going to try putting one in here, but I’m posting from kbin so it might go a bit weird or not exhibit the same problem.
!lemmings
It seems like the link you provided works just Like intended, altho I definerly have seen that bug. I think it was at a link sth like this one (links with ! and @):
!ich_iel@feddit.de