Airpods Max turn into mono mode after turning mic on

I have Airpods Max and using them with no issue together with Apple ecosystem. The problem appears once I try to pair them to Windows PC. Pairing is fine and sound is good... At least until I set Airpods Max' microphone as an input device (directly in system or in any app like Discord). Once set, headphones turn into mono mode with awful sound quality. I tried so many things to workaround that, but no luck.

What I tried:

1. Disabling mono in Windows' device manager, but then mic is just not working (as expected I guess).
2. Updating all the drivers.
3. Using external dual-band Bluetooth device.
4. Trying to use middleware app like Voicemeter to "mask" Airpods mic's input.
5. Completely reinstalling Bluetooth drivers and pairing headphones again.

Nothing works... It looks like it's firmware thing that immediately turns on **** XIX century quality once mic is active. I am so angry, because I bought those headphones instead of Sony to stay in the ecosystem (because I use multiple Apple devices together with Windows for playing games).

I was Googling and found hundreds of topics where people are extremely angry for that. Those headphones are so expensive that they should work perfectly without any issues. Come on Apple, fix that and update the firmware...