Unless I’m wrong, the unique thing here is that auth fetch is always off for the server. It’s on only at the user level and it’s only on at that level if a user has an active domain block.
That could actually solve a lot of problems for people. Admins are reluctant to enable it server-wide because it causes a bunch of problems. The biggest being that it breaks federation with servers running older software (Mastodon v <3.0 I think) and with other services (Pleroma, maybe others). It also uses more server resources. But there are always people who think it’s worth it.