1.Maybe you should check if the Redirect URLs in supabase are set correctly.

2.Check the web domain name setting of Service ID in Apple. The supabase documentation says that you need to add <project-id>.supabase.co

via: Login with Apple > Using the OAuth flow for web > Configuration

Configure Website URLs for the newly created Services ID. The web domain you should use is the domain your Supabase project is hosted on. This is usually .supabase.co while the redirect URL is https://.supabase.co/auth/v1/callback.