A reminder that you can encrypt the content of a push notification before it’s passed to Apple and then use a notification service app extension to decrypt the content before the notification is displayed to the user.
While this doesn’t prevent the government from tracking users through the metadata linked to a push notification, it does, at least, hinder their ability to access the content of the notification. https://developer.apple.com/documentation/usernotifications/modifying_content_in_newly_delivered_notifications/