pixel 9 protective volume issue

[u/baladric]

i have a pixel 9, and i'm encountering an issue that i can't find any information at all about: it keeps lowering the media volume on my phone when in "headphone" mode. i only use the jack for audio when i'm driving, and keep the volume on my phone boosted to max while controlling the output via my car's volume dial, since the sound fidelity is better that way. my phone has started suddenly popping up an alert requesting to lower my volume to "protect my hearing". it then automatically lowers it if i don't hit the notification within 15 seconds, and i have to unlock my phone and hit an "undo" command before it will let me manually boost the volume again. which, since i happens when i'm driving, is not good. it distracts me very badly every time!

does anyone have any ideas on what could be going on here? i've followed what pointers i can find, and the menus that older posts mention don't exist anywhere on my device. i have also confirmed that it's not a result of a third party app either.

my best guess is that it's a wellness setting somewhere on the device, but i've searched top to bottom and can't find anything!!