@BeAware @treefit Yes, that's easy to understand, thanks for the explanation.
Basically this means, I/my instance only sees comments in a thread, from people that are "known" to my instance (because someone on my instance is following them) or they have an account on my instance. Otherwise I have to take a look at the original post on the original instance.
Right?
PS: I suppose some apps (maybe #Fedilab) initially pull all comments together from all instances. But I'm not 100% sure.