Beehaw defederated from lemmy.world. So anything that a lemmy.world user posts on any instance in the fediverse will be invisible to beehaw users. Any posts made on the beehaw instance won’t be updated to lemmy.world users after defederation. The local “cached” version of various beehaw communities still exists on the lemmy.world instance, so we can view that and comment/post/vote there. However all that activity stays on our instance and is invisible to any users from all other instances.

In practical terms, it means we can’t participate in any beehaw communities. We can see posts made by beehaw users on other instances (say a comment by a beehaw user in a lemmy.ml community), but the beehaw user won’t see any posts made by a lemmy.world user.

It means we can't see/talk to them, and vice versa. You may still see old beehaw posts and comments, that were already cached on our side, and can even interact with them, but none of that data will make it to them

Everything on Kbin and Lemmy is "federated"

This is basically just a fancy word to say "no matter what server you're on, we can all talk to each other".

It's kind of like E-Mail where no matter if you use GMail or Outlook, you can talk to your friends and colleagues.

When a server defederates from another server, It's like a two-way block.

People on (in this case) beehaw won't see threads, magazines and replies from Lemmy.world and sh.it just.works and people from Lemmy.world and sh.itjust.works won't see threads, magazines and replies from beehaw.org

Server/Instance admins usually do this when there are instances which spread unwished for content.

This is also why on my profile, there's a link (forum.fail). It's part of my identifier here on the Fediverse (@[email protected]).