The Genshin website previously allowed anyone to view the phone number you have linked to your account via the password reset mechanism. Due to common reports of accounts getting stolen (and unable to be recovered), two factor auth has been highly requested, but doesn't seem to be a priority. I'm skeptical that they strongly care about the security of their users.
Even if Genshins anti-cheat is completely secure, as kernel anti-cheat becomes more common it's inevitable that we will get an instance that is full of security holes. Unfortunately as long as the user can't play their favorite game without it, they will happily install it.