What are the possible reasons to get APNs responses BadDeviceToken or Unregistered?

Question

When sending notifications to iOS users, for some of them I get response status code 400 (BadDeviceToken) or code 410 (Unregistered).

From Apple documentation about \"Ba

Answer 1

Feedback is no longer immediate with 410 notifications. Apple intentionally has done this due to privacy concerns. It may take up to a week now. See https://developer.ibm.com/customer-engagement/2019/05/01/apns-feedback-service-change/