My devices- Asus vivobook S15 OLED and Realme wireless 5 ANC{Neckband}
I had this same issue, where all Bluetooth earphones (neckband with mic) started showing just "connected audio" and no mic after updating windows 11 on my laptop in December. I did everything suggested to solve this problem but nothing worked. I have intel EVO Laptop
SOLUTION: First remove all saved Bluetooth devices from your PC. Then open device manager, go to "Audio inputs and outputs" dropdown section and remove all Bluetooth devices. then restart your device. These steps finally SOLVED MY PROBLEM.
In my case, it started showing "connected mic, audio" under my Bluetooth audio device name whichever I paired with my PC and in all others (Bluetooth earphones too) too. Mic also started working too as I did a zoom call after this process.
Hope it helps