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).
and on some level it’s important for good opsec that things that don’t require opsec be done with good opsec
That doesn’t work in reality, as evidenced here, it’s far more likely people compromise their security for convenience than the other way around.
Also sometimes opsec requires in get messages from certain chats quickly. Knowing where ICE are in a timely manner is important.