Constant car radio rebooting when iPhone connected

Ever since the iOS15.6 update I did earlier this week I can no longer get my car head unit to stay on when my phone is connected.

About 15 seconds after my phone connects and CarPlay loads, the whole head unit crashes and reboots, then there's a delay in CarPlay loading again after the car radio reboots, and then it crashes again. Repeats indefinitely.

I have tried two other iPhones; an iPhone 11 running the previous version of iOS and a 12 mini running iOS15.6. In both cases these other phones work fine. This makes me think it isn't a problem with my car radio (the common response in other forums is to update the software - but in that case why do these other phones work fine?)

What is going on? Does anyone have any ideas? I have tried resetting the settings on my iPhone and this did not work. I have also tried a full factory reset and this also did not work. Could this be a hardware issue? I have also tried two different genuine apple cables and neither work.

Really frustrated as this problem seems to have come about with the latest version of iOS on my phone specifically.