google pixel 9 pro with graphen os

Easyjetholliday

have a Google Pixel 9 Pro running GrapheneOS. Sometimes, I experience a problem where I don’t receive messages, and no notifications are triggered. It doesn’t happen all the time, but occasionally it seems that the app only connects and retrieves the messages after I open it manually.

c86

Easyjetholliday

This is just how things are for AOSP generally. Notification protocols aren't integrated like say iOS enforces.

It could be the app has a glitch in communicating with servers while running in the background, obviously resolved when you open the app. You could try adjusting battery optimization settings for that app. It could be a data issue if you're behind a VPN - I've had delays on occasion until I've cycled a VPN connection.