Hi there! Looks like you linked to a Lemmy community using a URL instead of its name, which doesn't work well for people on different instances. Try fixing it like this: !accidentalrenaissance@lemmy.blahaj.zone
FWIW, in Memmy, the latter is recognized as a URL and clickable, but takes me to a “page not found” page on my home server. The former is not clickable.
I think that may happen when those communities haven't federated on your instance. You should be able to copy the link and search for it on your instance, it usually takes several seconds for it to appear because it needs to resolve the link to the community.
Once someone is subscribed to that community in your instance, those links should work as expected. At least, that's my understanding of it.