Defederating in this situation means (to my very limited understanding). Users on lemmy.world can see posts from beehaw.org, they also can interact with the posts/comments. Those interactions just don’t show up on beehaw.org, so that they don’t have to moderate as much.
Reddit charging a metric ton of cash for their api is more or less if you would have to pay (the creator of lemmy) for each user if you decide to create your own instance (lemmy.world, beehaw.org and whatnot).
I think defederation works both ways, the posts you can see from lemmy.world are old copies, not being updated anymore.
You might be right, but I understand it so that beehive is still providing the true to everyone, just lemmy.world users can’t interact with the true version they will get an out of sync version with only their comments. But lurking should be still possible. Basically similar to a silent ban. You can still post but (almost) nobody can see it. (almost means only lemmy.world users)
Since it is out of sync .world users and sh.itjust.works users can also not interact on beehive posts since they both have their own out of sync copy.
