Hmmm, maybe it’s a toyota thing… I have an Auris (also pre-android auto), and recently the music, over bluetooth to the car, speakers still works for me, but the incoming phone calls no longer work. The caller can hear me, but I can’t hear the caller any more.
I have the same problem on my fairphone 6 with e/os 3.7.1
When getting a call (with music on is the only I tested), the app will show Bluetooth speaker but will use the frontal (above the screen camera) speaker instead. When making a call it works property. I also tested this on signal, and in that case when making a call from the signal app it still has the same issue, even trying to switch to the bluetooth speaker doesn’t fix the problem, and it lags and acts weird instead.
I don’t think its my car problem, because I had no problems with my old realme 6 pro.
Also my bluetooth headphones has no problems receiving a call.