The personal fix is to block that community, or set up such that you see subscribed communities by default.
The broader fix would be made to Lemmy itself, and I’m not sure anything like that exists. It would require the same concept as a “default subreddit”, which I’m pretty sure Reddit built as a checkbox their admins can control as to whether a community shows up if you’re not logged in.
Lemmy is still going through growing pains and doesn’t have a large user base yet, so I wouldn’t be surprised if a feature like that doesn’t show up for a long time. We’re probably on our own until then.