I have been having this issue since I bought my 2020 Sierra a couple of months ago. I searched around the forum and found other Bluetooth issues, but I couldn't find this specific problem.
I generally always have the media volume on my phone at 0 to prevent any audio from accidentally playing. Every time my phone connects to my Sierra's Bluetooth and I make/receive a phone call, once the truck is off and the Bluetooth disconnects, the media volume gets set to max.
I have tried a few different devices, and it seems like it may be isolated to Samsung devices. It's not an issue on any Apple devices, but it happens every time on a Samsung S20+ 5G, Samsung Note10+, and Samsung Note20 Ultra 5G. On each Samsung device, I have tried disabling absolute volume in developer settings, but it makes no difference. I have also tried resetting the infotainment system, factory resetting the Android devices, forgetting/re-pairing, and none of these have made a difference.
I'll be trying out a Pixel 4 XL today in an attempt to determine if it's an issue between all Android devices or only Samsung devices. I also own a 2018 GMC Acadia, and these issues are not present on it, which is understandable since the infotainment hardware and software is different.
Has anyone else seen this issue, and if so, found any resolutions?
Edit 1: My vehicle is a 2020 GMC Sierra SLT 5.3L w/ navigation & Bose audio.
Edit 2: Tested with a Pixel 4 XL and the media volume did not change like the Samsung.
