@thisismissem @dansup it's all using public information that instances already know about and store in its database.
If you were dansup and trying to evade serial trolls you might consider signing up under a different name rather than the same one being harassed.
@cooopsspace @dansup right, but I could be running in limited federation, but need to be federating with pixelfed.social, and the act of doing that would allow all the other instances that I've not federated with to know where I am.