I've tried searching for other posts that ask a similar question, but I couldn't fine one that could fully make me understand what it would mean in this scenario.
So far from my understanding is that if I browse All, the instance I'm on won't show anything at all from the instances that it blocked. But manually doing the workaround would still show me the community and whatever posts that got federated in my instance. Is my understanding correct?
The other topic of federation that I'm interested to understand as a user are below.
The example: fedia.io states in their federation list that it does not federate with ani.social. But ani.social states they federate with fedia.io.
I can go to say !anime@ani.social just fine via fedia.io, although there is some posts that doesn't show. Is this one of the result of this situation?
Additionally, today I did basically try to subscribe to all the same communities/magazines on my lemmy.world (I'm considering to abandon this account), fedia.io and kbin.earth accounts.
Other than the situation above happened to some communities where some post doesn't sync, I've also found some communities that's just inaccessible from either 3 instances.
It means both instances will see old posts from before one of them defederated.
Now that A is de-federated from B, they both won't see new posts or comments from eachother. In the case of fedia and ani.social, you won't get any new posts from any of their communities or users. If you post on anime@ani.social from fedia, nobody will see that post outside of fedia users, because ani.social isn't seeing it and passing it around to the rest of the fediverse.
You hav basically the right idea, everything stops syncing when one defederates.