Sign in with apple has an option to obfuscate the data being shared with the devs, so we get this random relay like 89yzx94n77@privaterelay.appleid.com. We ask for name and email again in case
Asking for email after sign-in with Apple is against their TOS. At some point when you release an update they'll notice and require you to change this. (It happened to me ~6mo after we launched!)
The point of enabling that option is that users want you to use the relay so they don't have to give you their real email address. If you're just trying to send an email, why isn't the relay acceptable?