I haven't looked at it but I would hope that "Sign in with Google" provides the service using it with a stable ID other than the email address. But I can also s

I haven't looked at it but I would hope that "Sign in with Google" provides the service using it with a stable ID other than the email address. But I can also see services ignoring that and just using the email address anyway... If such a service only saved the email address when the user account was created it might be very difficult for them to fix this unless the do it really quickly and I happen to sign in to their service before all of this goes down.