@QuentinMann
They are connected to the Fediverse and The Federation (two different things). But many instances probably have blocked their whole instance and it's surrounding affiliates.

We as users can do that on our own accounts - if you search for a user in any domain, go to their profile from here, by clicking the search results.

The dot menu "..." has the option of Blocking that whole domain.

I posted the steps and screenshots here yesterday for a user irked with porn domains.

@n0btc