How Does manage Firebase, Apple sign ins without account email associated

[jesus-mg-ios]

Hi:

I was reviewing "sign with Apple" Flow because a few users told us about a "sign up not completed" error.
So I'm wondering how Firebase manages the cases when the user's Apple ID has no email associated and if it possibly ends on this error.

As you can see in the video, the scenario could happen: https://developer.apple.com/videos/play/wwdc2022/10122

[jesus-mg-ios]

Also, I want to know if the notifications server to server is a service available in firebase and where I can find the url