In a note on its Developer Webpage, Apple notes that if you send push notifications with the legacy binary protocol, we recommend updating to the HTTP/2-based APNs provider API as soon as possible.
The tech giant says “you’ll be able to take advantage of great modern features, such as authentication with a JSON Web Token, improved error messaging, and per-notification feedback.” The Apple Push Notification service (APNs) will no longer support the legacy binary protocol as of November 2020.