New iPhone 12 car bluetooth issues...

I recently upgraded my iPhone 11 to the new iPhone 12. I have a 2009 Chevrolet Avalanche with Navigation. I cannot get a stable connection via bluetooth to my iPhone for handsfree operation. My iPhone 11 worked just fine. I've also tried to connect to two other vehicles, 2011 Honda Pilot and 2014 Honda CR-V. I have had the same issues with those vehicles. My daughter also has a new iPhone 12 and has the same issues. My wife has a new Samsung s21 Ultra and it works just fine with the Avalanche and the CR-V. My phone appears to be pairing just fine, but if I try to make a call it will not make the call correctly...cuts in and out, dead on both the phone and the car audio, etc. It has worked a few times, but just a few times.

I've looked all over the internet and have tried all of the suggestions that I see out there. I've reset the phone and the car audio. I've upgraded to IOS 14.71, but that didn't help.