It gives this warning when I install through obtainium. Play protect is a system service, like an antivirus kind of. It works regardless of the install source. It uninstalled robosats without asking me prior to this. 

 Ok but you can force install it so it's not so bad. But the fact that it can uninstalled chosen app is indeed frightening lol 

 It actually uninstalled twice today. I reinstalled it this morning to take a look, and after work it had been removed again. You may be able to install it, but how long will it stay 😬