I just created the !realmadrid@fanaticus.social commuity for football/ real madrid fans and have had a decent number of subscribers in a day. I still dont know how to get more people in tho, especially active members who would post. Yesterday was surprisingly good since I made a post on a bigger football community basically advertising my sub and it was gamenight. Any tips?
You should only do this on a couple of the big instances. You shouldn't force a community to federate to everywhere. If someone wants to see it, they'll sub.
And it's not really an issue, it's intended behaviour that makes it so that each instance only federates the minimum needed. It saves on instance traffic and storage.