I've seen this issue a bunch on the forum, but there is no definitive answer to fix it. Attempting to sign in with UnityHub redirects me to a login page, which redirects to a blank API page that does nothing. The binary has no command-line arguments as far as I can tell. I've downloaded older versions of the editor, but they still open up the newest version of the hub. Unity on Linux is borked apparently! I last worked on a project about 8 months ago and had no issues, and have been using Unity on Linux for years, so this is a very frustrating development.