They defederated with multiple large lemmy instances (lemmy.world and another I don’t remember). They also did this in an asymmetric way making themselves an island whose content gets sent out into the fediverse but who doesn’t listen to updates for the content that gets sent out.
If I comment on a beehaw post as a lemmy.world user, my comment will only live on lemmy.world and not the rest of the fediverse because of what beehaw did
That’s not how domains work.