I use a .dev domain for my main email address, and I occasionally encounter sites that don't accept it as valid. Even worse, sometimes I could create an account

I use a .dev domain for my main email address, and I occasionally encounter sites that don't accept it as valid. Even worse, sometimes I could create an account but then something would be broken, such as when I could log in to Best Buy via their mobile app, but not their website (or vice-versa—I can't remember for sure). I'm assuming I get hit both by incomplete whitelists and ill-advised blacklists.