In the App Store guidelines it is stated as mandatory to provide sign in with apple. Is the app allowed to block users who register with "hide my email" and not allowing them to create an account?
https://developer.apple.com/app-store/review/guidelines/#sign-in-with-apple
From https://developer.apple.com/sign-in-with-apple/
Respect for privacy
Sign in with Apple was built from the ground up to give users peace of mind about their privacy. Data collection is limited to the user’s name and email address, and Apple’s private email relay lets users receive email even if they prefer to keep their address private. Apple won’t track users as they interact with your app.
Displaying a Sign in with Apple button in your app or website means that people can sign in or sign up with just a tap using the Apple ID they already have, and skip filling out forms, verifying email addresses, and choosing passwords. In cases where you choose to ask for a name and email address, people have the option to share a unique, random email address that automatically relays messages to their personal email address.
I can’t imagine a situation where it’s preferable to prevent a customer from using your service simply because they chose to keep their personal email address private.
—Jason.
