The problem has to be android auto on certain android device. Not ford's units. I'm afraid you're just getting lucky or your phone isn't an issue. I tested it again today with my own devices. I picked up a call on my s21 ultra while connected to android auto. And shut the door, and talked while on another phone. I could hear myself talking, it was echoing. After further investigation the phones microphones are for some reason getting activated causing the echo. Seems to be a priority issue, I don't understand why the phone would even be granted microphone access while connected via USB to android auto or even Bluetooth.... specifically speaking with phone calls. Anytime you toggle to handset, or speaker then back to Bluetooth the echo is gone. I sat in the car for about an hour messing with settings on the phone with no luck. I want to capture a bug report and have samsung and android autos team look into this.
Tons of people have this issue, and it's not just ford vehicles.
For those that think they have fixed it. Try getting in your car, wait until Bluetooth connects, then plug the device in for android auto and see if the echo is there. If I plug my phone in first then start the car 9 times out of 10 there's no echo.