I wonder if it’s because !lemmyworld@lemmy.world sidebar and rules say:

This Community is intended for posts about the Lemmy.world server.

That means announcements from the team, issues you see etc.

There’s so much spam in this community already. People are using it as a catch-all community

Yep! I’ve had issue direct searching for kbin communities here and communities from here on kbin though. I think that kbin federates very slowly.

Examples:

https://lemmy.world/c/apple@kbin.social

https://kbin.social/m/apple@lemmy.world