While Android allows you to customize all strings in a push notification, including title, iOS does not allow push notification titles to be modified.

This means that, for iOS, the title of a ‘New Message’ push notification (that is, a notification received when the app is closed or backgrounded) will always appear as ‘[App Name] Support’:

You can, however, customize text for in-app notifications (that is, notifications received while the app is open) for both iOS and Android.

The default title for in-app notifications is “New Message [s] From Support”: