Speech to text not working in my car

I have an iPhone 15 Pro that is current on all updates.  Speech to text works fine when I am not connected to my car.  In fact, until recently, it has worked with all prior iPhone models in my 2010 Volvo.  However, in the last few months, once I connect to my car and press the microphone in Messages and Email, the microphone is not receiving any input when I speak so I cannot dictate Messages while I drive (I have to turn the car off to get it to work).  Otherwise, my car’s Bluetooth works fine -- no problem making/receiving calls.  Of course, I’ve turned Bluetooth on & off, and restarted my iPhone.  Does anyone know how to fix this?