TLDR: signal content in Apple notification can be retrieved even after signal app deletion.

I saw from this reddit thread: Signal messages retrieved from iPhone after uninstalling app. : signal

Referencing this news article: Pretti Killing May Affect ICE Prairieland “Antifa Cell” Terrorism Trial

The mention of signal is in court documents here: March 10: Federal Trial Day 12 - Support the Prairieland Defendants

Signal chat evidence from Sharp’s device (Exhibit 158):
Messages were recovered from Sharp’s phone through Apple’s internal notification storage — Signal had been removed, but incoming notifications were preserved in internal memory. Only incoming messages were captured (no outgoing).

This is not always the same on Android. Any app from FDroid will not use Google’s push notification service because it is proprietary, meaning it violates the rules for FDroid. Signal does not use Google’s notification service

It’s not because of push notifications. the message is not sent to firebase, just a signal that the app should do a refresh. It’s because the system saves the notifications apps posted to the notification menu.

It’s not because of push notifications. the message is not sent to firebase, just a signal that the app should do a refresh. Is is 100% because of firebase. Here is an example payload from firebases official document: { "message":{ "token":"bk3RNwTe3H0:CI2k_HHwgIpoDKCIZvvDMExUdFQ3P1...", "notification":{ "title":"Portugal vs. Denmark", "body":"great match!" } } } firebase.google.com/docs/…/set-message-type Notification history is purely local to the device. It is not sent to any servers.

that is the documentation of firebase, not signal. firebase just shows a common example there that is easy to implement for beginners and lazy devs. but developers can send whatever they want through firebase. I wouldn’t be surprised if that’s what facebook messenger is doing, but if a developer cares about their users privacy, they can just send a simple message through firebase, and make the app so that when receiving that, it checks for new messages by itself. this is what the molly fork does with unifiedpush. the UP server, commonly ntfy.sh, only sees that the mollysocket server sent this to your molly client: {"urgent": true} Notification history is purely local to the device. It is not sent to any servers. I did not claim so. but when your phone is confiscated, it’s possible to read that out