I have the same issue with Volvo XC60 and iPhone 12 on iOS 14.6. - car dashbord freezes (needs to shutdown the engine and start again), unable to make calls/accept calls really wanted to throw the iPhone out of the car's window!!
My solution:
Switched back to my old iPhone XS Max also on iOS 14.6 and the problem is gone.
It's sad that I had to give up my new iPhone 12 and go back to the XS Max. I hope it's software related only issue, but starts to seems like a HW issue with the newer iPhones!
David0
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