This does not fix the issue that is the subject of this thread; i.e. loss of hands-free mode.
To test this:
* In Windows11: Perform the bluetooth troubleshooter
* In MS Teams:
- Settings -> Devices
- Choose Sony wh-1000MX4 headphones as speaker (there used to be a hands-free profile but this is gone now), Yeti mic as microphone.
- Make a test call. No audio is heard.
If the WH-1000MX4 is used for both speaker and mic MS Teams works as expected.
This thread is about the loss of hands-free mode that allowed the headphones to operate with a different mic.