Why do the instances keep going down? It makes me think that this is not a reliable social network, but the alternatives are not as good.
The difference is that ActivityPub clients currently only display the username part and hide the host for some reason. This can lead to confusion, I don’t get why the full address isn’t displayed by default.
Email does that too. It’s even worse, you can make “support@microsoft.com” show up but it’s really badguy@somewhereelse.com. Granted, many emails hosts are getting better at flagging these, but one can still click the name to confirm on Kbin or Lemmy.