Car Android screen wireless silences jack audio

I have a Samsung Galaxy S10 Plus and an Android car screen that I bought recently. My car is a Mazda 3 sedan 2018 (display with no touchscreen). The head unit is connected to a DSP, amplifier, and 2-way 6,5" components. This is because I'm always looking for a better sound quality, therefore I reproduce music with my phone through DAC Fiio Q11 which sends the clean signal to my car head unit via a 4.4 balanced jack cable. The problem comes with the Android car screen. When I connect it to my phone through BT, everything works fine except the music because the screen starts playing with its own internal speakers even when I disable the audio option in BT settings. Also, I try to go to individual external player settings and set it to play music only on my phone, but the problem remains. So I was searching for this kind of problem and didn't find any solution. I have tried 4 Android apps and still nothing. So I wonder, how can I lock the BT audio output in order to force the audio output of my phone?