I am using this Pixel 6 Pro as a test to see if GrapheneOS is for me. So far I like it, except for one thing: My sound settings are reasonable. A call is fine, any IM asking for my attention is okay.

But occasionally I have a "RIIIIIIIIIIIIING" sound that completely bypasses all loudness settings and likes to come at any time of the day (fun if it's the early morning). My assumption so far is that it's related to the system updater, but honestly I don't know and don't care too much: It's effing broken.

Is there a way to avoid getting screamed at in the middle of the night? If not, I guess I have to flash back to stock to find peace and quiet.

Are you using multiple user profiles with the notification forwarding feature?

If you are, check whether the sound is coming when you get a notification from a different profile while you're in another.

If that is the case, and what's triggering it is the "Apps" app notification, or the system updater notification, you can disable that notification channel for both apps by long-pressing the notification, pressing "turn off notifications" and then disabling the relevant notification channel.