User is not created in AWS Amplify User Pool using federated sign in

[iOS15, SwiftUI, AWS Amplify]

I'm using a

SignInWithAppleButton(
    .signIn,
    onRequest: configure,
    onCompletion: handle
)
    .signInWithAppleButtonStyle(.white)
    .frame(height: 44.0)
    .clipShape(Capsule(style: .continuous)
)

to call a handle function, that calls this signIn function:

func signIn(with identityToken: String) {
    guard
        let plugin = try? Amplify.Auth.getPlugin(for: AWSCognitoAuthPlugin().key),
        let authPlugin = plugin as? AWSCognitoAuthPlugin,
        case .awsMobileClient(let client) = authPlugin.getEscapeHatch()
    else {
        return
    }
            
    client.federatedSignIn(
        providerName: "signInWithApple",
        token: identityToken) { state, error in
            if let unwrappedError = error {
                print("Error in federatedSignIn: \(unwrappedError)")
                return
            }
            guard let unwrappedState = state else {
                print("userState unexpectedly nil")
                return
            }
            print("Successful federated sign in:", unwrappedState)
        }
    }
}

The console prints Successful federated sign in: signedIn, but when I check the User Pool in AWS Amplify Admin UI or AWS Cognito, it is empty.

AWS Admin UI:

AWS Cognito -> User Pools -> Federated Identities:

Any ideas what I may be doing wrong?

Debugging HTTP traffic, I found out there was an error message that is not returned by client.federatedSignIn(). The error indicated the identity token did not match the provider, so I decided to try with several different options for the provider name, and the one that works is: appleid.apple.com.

    client.federatedSignIn(
        providerName: "appleid.apple.com",
        token: identityToken)

or

import AWSMobileClientXCF
...
    client.federatedSignIn(
        providerName: IdentityProvider.apple.rawValue,
        token: identityToken)

Doing further research I also found out a user is not created in the User Pools when using federated sign in. This only happens if using credentials sign in, or social sign in using Hosted UI.