>it's even worse than that. What's additionally happening is they're still 'syncing' back to Apple servers via APNS (and to Alphabet servers via Firebase on Android)—even with notifications completely disabled, that's correct.
Source? I don't think either OS implements notification syncing between devices, it's only one way, and as others have mentioned, the actually push notification doesn't contain any message content, only an instruction for signal to fetch and decrypt the message.
This sounds correct. When I implemented push notifications for an iPhone application, I remainder needing to obtain a store a separate token for each device a user has, and subscribing to a feed of revoked delivery tokens. Seemed like an interesting design intended to facilitate E2E encryption for push notifications.
Source? I don't think either OS implements notification syncing between devices, it's only one way, and as others have mentioned, the actually push notification doesn't contain any message content, only an instruction for signal to fetch and decrypt the message.