Comment by ImPostingOnHN

Suppose you use an anonymous app for messaging. The government sees the conversation ("good day to you") but doesn't know who is on one side (perhaps both).

So they ask Apple "who exactly sent or received on their phone a push notification for 'good day to you'?" Or perhaps "who sent or received push notifications from secure messaging app around 8:24:39.124 pm, 8:26:12.322, etc.?"

Apple tells them, and now they know the identity of the "anonymous" recipient. Replace "good day to you" with any text disliked by any format or current or future government.