judicial709 com.aluntapps.rainsounds
This app has a built-in timer which by default is set to 20 minutes. It can be turned off manually, but if you pause and resume the sound that is playing, it will start a new timer without displaying a confirmation prompt. Please confirm if the issue occurs when the timer is set to "off".
I couldn't reproduce the issue on a Pixel 8 nor on a Pixel 6a running 2024110700. The 8 was left alone for a whole night with the timer set to off and app battery usage set to unrestricted, and it was still playing when I woke up the next morning. Even with the app battery usage set to optimized after an app reinstall, it continued to play happily without me interacting with the phone before I manually turned it off after an hour.
You will have to provide a full list of the apps you are having issues with, as well as the app battery usage settings they are set to. Without further information it's not going to be possible to reproduce the issue. Please also provide the GrapheneOS version, and whether or not developer settings are turned on and whether or not you have used adb to run commands on the phone.