I have a 2019 Blazer and this happens everytime I entered the vehicle. I have an iPhone Xs and am running iOS 13.3. My husband just bought a 2020 Silverado and his iPhone Xs doesn't do this. He is also running 13.3. Did they fix the problem with the 2020's? I hate having to remember to turn my volume back up when I leave the car. It does this no matter if using bluetooth or carplay.