Notifications for deleted shouldn't remain in any OS notification database, and we've asked Apple to address this.
In the meantime, you can prevent any preview text from your Signal messages from appearing in your notifications.
Signal Settings > Notifications > Show “No Name or Content”
Meredith Whittaker
NEW: The FBI was able to forensically extract copies of incoming Signal messages from a defendant’s iPhone, even after the app was deleted, because copies of the content were saved in the device’s push notification database, multiple people present for FBI testimony in a trial told 404 Media.
The case was the first time authorities charged people for alleged “Antifa” activities after President Trump designated the umbrella term a terrorist organization.www.404media.co
