It’s pretty easy to sum up. The admins on beehaw decided to break federation with a couple of other instances including lemmy.world. Their reasoning being that the open registration policies and relative lack of oversight in those instances were incompatible with the space they wanted to create on beehaw. What this means is that users from lemmy.world cannot interact with users on beehaw and vice versa.
The technical details of how all this works are a bit more complicated, but that’s the basic gist.
As a lemmy.world user, will I still be able to lurk beehaw communities? Or will they not be updated on my instance? In other words, is defederation directional or static?
In a way, but the details are complicated enough that I’m a little fuzzy on how it all plays out myself. As I understand it though lemmy.world users would be looking at the version of the beehaw community that is stored on lemmy.world. They can view and even interact with posts and communities as if nothing had changed. However, any content they generate would not leave lemmy.world. Additionally there are details regarding how certain communities start being hosted that I am unsure of.