Microsoft Teams Bluetooth Headset No Sound When Using External Mic

Nope, none of the above is a 'solution'. Workaround at best, but even then, some just do not provide the full and proper experience. Disabling the Handsfree Telephony under the BT headset/headphones (regardless of make and model) does not provide audio switching.

Example:
When you are listening to music on your smartphone with your BT headset/headphones and then you get a Windows notification sound it should either suppress or temporally pause the music playback. On a Teams call, since it is using both playback and recording function of what Windows sees it should pause the music playback. When the Teams call ends, music playback resumes.

This has been my experience under Windows 10 and Windows 11. However, when using any mic outside of your BT headset/headphones (e.g. Rode XDM-100, Blue Yeti, etc.) this is not the experience with Teams and Windows 11. Teams and Windows 10 still work fine with the above scenario. So, I suspect that this is a combination of the two. Microsoft is trying to make the Teams and Windows 11 Experience the most optimal, but this is not working out so well and I do believe that they should not be controlling the audio (aka Unified Audio Endpoint).

This is ok for consumer and/or novice users, but for us technical users we should have more control if we want it.