Hey, I use Pixel 6a with stable grapheneos. Everytime, the phone downloads an update, I get a notification, then a permanent notification about rebooting the device to apply the update. But since several days, I did not get it, and now I rebooted my phone for other reason. It was on the grapheneos logo for a loooong time, and after it was done booting, I saw notification about update, and more shockingly saw that my phone update to android 16 from 15.
I dont think this has happened before that I did not get a notification to reboot my device, and I only reboot when I have to update, so I went for many many days without knowing my phone had downloaded an update.
If you want any logs, let me know