Kindly if you use Andriod Auto app, go to Settings - Apps - Andriod Auto and Clear Cache.
Make sure your mobile is updated to the latest update from the following path:
Settings - Software version.
Try to connect different device in the car, to help isolate the issue cause, as it might be from the Car, and check if the car system needs an update.
Please note that when I started getting this issue around 2 weeks ago, I took the car to the dealer who inspected the car system and tried it and could not find any fault in the car system (the vehicle is 2022 model).
When I brought the car home from the dealer I tried the car system with iPhone 11 Pro max and iPhone 12 and they both worked fine with the Bluetooth car system.
Today after clearing the Android Auto cache I tried through the Bluetooth but the problem was still there, but when I tried through the Android Auto app. it worked fine.
It seems the problem is with my Galaxy 21 ultra 5G Bluetooth.
One thing to note I always keep my phone updated with the last software update, and the problem started to appear with my car after I installed the latest update