And are usernames unique across instances or can anyone copy anyone else's username by signing up somewhere else with the same name or just making a new instance?

The top level domain of the Metherlands

RIP RIF

tbf i didn't actually stop using redditisfun. I followed the guide to patching RIF with revanced which changes the user agent of the app to hide from reddit that you're using redditisfun

The instructions are here https://www.reddit.com/r/Android/comments/14niwgu/revanced_patches_for_boost_infinity_rif_is_fun?sort=new

Gonna plug revanced here, too, since i already had revanced because i use it to have adfree YouTube and YouTube music with unlimited skips. Been using it since it was called vanced, when they just shared modified APKs. Then Google shut them down with a cease and desist letter so revanced was born. It's a system for patching apps yourself which gives the developers a bit more legal cover.

Revanced.app

GitHub.com/revanced