I'm noticing that new posts, comments and especially updates to posts and comments and votes are not pushed to the origin of communities which lemmy.world users have subscribed to. Or at least it takes many (>> 10) hours.
Just pick a random community that is not local to lemmy.world and compare the local copy with the origin. I would be surprised, if you don't find tons of comments from lemmy.world users which have not been pushed yet.
The result is a lemmy.world bubble in which lemmy.world users see posts and comments from each other but nobody else does.