I'm looking at beehaw communities on both Lemmy.world and Beehaw.org,and they're totally out of sync with each other. There's the rare post from a beehaw user that breaks through somehow - possibly boosted from a kbin or Mastodon instance? - but for the most part, you're getting basically none of the content from those communities.
Because beehaw isn't sending you any updates.
Is it that you're seeing beehaw users who are posting to communities hosted on 3rd party communities? Because that's absolutely possible.
And that's absolutely the issue with federating with sites that continue to federate with instances you've defederated from. You're blocking direct communication in both directions, but there's a lot of indirect communication going on.