An upstream issue was reported to GrapheneOS describing how the on-board volume control for some USB-C audio devices is set to 50% on every power on. This includes the Apple USB-C to 3.5mm audio dongle and maybe other devices.
https://github.com/GrapheneOS/os-issue-tracker/issues/4373
The Github issue linked to the discussion here https://issuetracker.google.com/issues/242221770. Someone from Google recently closed the issue as fixed. Multiple users confirmed it's fixed on the stock OS with Android 16.
Can anyone confirm that this is now fixed in GrapheneOS's version of Android 16 so that the Github issue can be closed?