Static sound in cars when playing music from my iPhone, but not with other phones…

Hi.

I have for a long time been experiencing issues with static sound coming from the speakers in multiple different cars. My own BMW, my work Toyota, and multiple different cars. I have a iPhone 11 Pro.

What happens is, when I connect with Bluetooth I usually turn the volume up to max on my phone so the quality is better in the car. But when I do that, there comes a static sound that is extremely annoying. The same happens if I connect with a USB cable, whereas the sound is automatically set to max on the phone. However, compared to Bluetooth, the static is even more intense. Also, the more the sound is turned up in the car, the more the static. However, over Bluetooth, if I adjust the volume down with nothing less than 4 clicks, then the problem disappears.

What is interesting is that, when connecting other phones, like my dads and girlfriends Samsung and moms iPhone, this is not an issue at all whatsoever.

Yes, I have tried the turn Bluetooth off and on again after multiple seconds solution. I have restarted my iPhone. I have checked for updates and I am on the latest version.

So… now I have come here in hopes for help that will finally work.

Any thoughts?