If your server hosts communities that follow others, that would still be the same as having users on your server follow those servers. It’s the same amount of communication.

Oh that's a very good point! I had the wrong impression there was extra data sharing needed in this case but yeah, looking back it makes sense that the amount of data transfer is about the same considering the focus is on the verb (actor A sends to / pulls from actor B) rather on who is doing the action.