Aux just started being messed up
So my phone started recently playing quieter on aux in the car, its just way down and everything is suppressed over how it was before at all the same volume , it does however play louder on a different phone, it was how mine did sound, both iphones, i did get a new aux cord didnt really help, and pretty sure not the dongle piece since i had a plugin one piece with the aux and lightning cable in one , but it will sometimes play normal or just louder at least for maybe 20 minutes max then go down and i can really hear it in the bass, help would be appreciated
iPhone XS