This is probably not a common problem because I assume most people don't play Galaxy of Heroes in their car. This comes up for me while waiting to pick up one of my kids from work, or band practice, or something similar.
I have a 2018 Honda Accord that uses Android Auto when I plug in my Galaxy Note 20. If I am listening to the radio and I open Galaxy of Heroes while plugged into the car, then the game switches the audio on my car and I cannot switch it back to the radio as long as my phone is plugged into the car. If my phone is already charged then it is not a big deal, I can unplug my phone and play the game and listen to the radio at the same time.
Regardless, it seems like the game should not be able to control the audio functionality of my car through Android Auto. It previously prevented me from listening to music from other apps as well but that was fixed in a previous update but this specific issue still exists.
