FBI Extracts Suspect’s Deleted Signal Messages Saved in iPhone Notification Database

Play Store version uses Google’s push/FCM but yeah even then it’s just the generic ping data they get as I understand it. Some may not even want them to have timestamps, so there’s solutions to that:

Can take it a step further grabbing the non-google APK on their website instead or using the hardened Signal fork named Molly. Both use a persistent WebSocket connection to Signal’s servers instead.