AudioManager.isBluetoothScoOn returns wrong value

Question

I don’t have much knowledge about Bluetooth. As android documentation lacks details I'm really confused about this. I'm trying to route a webRTC call to a Bluetooth headset. By calling am.startBluetoothSco() I can route the audio to the BT headset successfully. But when I read the value using am.isBluetoothScoOn it sometimes returns false, even if the audio is playing through the BT headset. So, my questions are,

1. How can I get the current SCO state property?
2. What is the difference between setBluetoothScoOn() and startBluetoothSco()
3. What is the difference between SCO, A2DP, and BLE (Bluetooth low energy)?
4. Should I need any extra permission to make this work? (I learned that android 12 has some changes regarding Bluetooth)

Thanks.