You probably need to make a request to Izzy. From what I remember he has requirements, such as max app size, which makes me wonder if maybe the ProtonMail app just became too big for him to build and host.
Here are the requirements: https://gitlab.com/IzzyOnDroid/repo/-/wikis/Inclusion Policy
For the known top trackers, it’s to have more control over nefarious users such as duped accounts, banned users and potential law enforcement trying to sign up. Sure it’s not a bulletproof solution to deal with bad actors but it’s still an effective way. You gotta remember that these trackers are free (yet private). The admins/operators don’t get paid, so last thing they want to do is waste time dealing with such users.