(Please correct any misunderstandings below.) From my limited understanding of the fediverse, for each thread that exists, every instance will host its own version of it. This instance-specific version will collect comments left from users from all instances in the “world” (whatever that means here). The exception is if instances block other ones.
But what about this random thread:
https://sopuli.xyz/post/683221
The first is the original (which is confusingly posted in a community at Beehaw, but I believe the original is at sopuli.xyz because the user is registered there). The second is the version on lemm.ee. Why do I see 13 comments for lemm.ee and 18 for sopuli.xyz? One comment that I do not see on lemm.ee is by a user on sh.itjust.works. This is not a blocked instance. Is it because lemm.ee needs to pull from all instances periodically, and this is just a cached version? If so, how often are these updates, and is there any way to see a timestamp of the cache for an individual post?
You can see exactly which instances are federated or blocked from an instance by going to the instance with /instances. So for Beehaw it’s https://beehaw.org/instances and for lemm.ee, it’s https://lemm.ee/instances. It looks like they’re both federated to each other.