iPhone 12 Bluetooth failing to auto connect to 2013 Hyundai sonata

iPhone messed up its Bluetooth software. It’s very horrible to connect each time when I get in my car. iPhone doesn’t recognise or auto connect to my car Bluetooth. Things I tried to fix.

1) Tried re-setting Bluetooth connection. Forget the iPhone from Bluetooth list and re-connected several times. It connects for the first time and the second time it will not work. I have to pair again.

2) Re-started my iPhone several times.

It connects for the first time and the second time it will not work. I have to pair again.

3) I tried re-starting cars audio system.

It connects for the first time and the second time it will not work. I have to pair again.

4) updated to latest IOS every time and tried again. It connects for the first time and the second time it will not work. I have to pair again.

5) This time I tried my friends Samsung galaxy phone. It never caused an issue. It connects as soon as I get in my car.

I am a long term user of iPhone. It did not happen with older versions like iPhone X.

from the above point 5). It clearly proves that the issue is with IOS but not sonata audio system.

Please do not close this issue until you have an answer. Thank you.