Hello, I understand that you disable the hands free mode but it gets renabled when you restart right? Thats a normal behaviour. Now here's the full context, skip to bottom for solution.
This behaviour was not in windows 10 because the audio profile selection was manual, for example, when connecting a bluetooth headset on win 10 you had basically 3 devices, two audio outputs (headsed stereo and hand free) and microphone. Someone at windows had the great idea to make this automatically managed by the OS (read horrible idea). So now when connecting a bluetooth headsed you only have 2 devices (microhpone and headset) and windows "automatically" chooses the best bluetooth profile. This was made to make things easier for the user (read solving a problem that nobody had by creating another problem)
Games like COD, for example, always activate the "hands free profile" when you active voice chat (they tell the OS "hey, Im on call, give me a hands free mode plz") and the only way to do away with this is disabling the hands free gateways on services, disabling hands free telephony on you device or disabling the hands free drivers for the device. Every single option disables some features on the headset but solves low audio quality problem.
Now, I've seen you tried everything but the gateways. Now on windows there's a service called "Bluetooth Audio Gateway Service" this bad boy is what supports the "hands-free" mode. By disabling it you basically deny any hands-free mode on any device you connect and like most services, the modifications are permanent till you change them.
Description: "Service supporting the audio gateway role of the Bluetooth Handsfree Profile."
Steps to disable:
1.-Search "services" on seach bar or press WInd+ R to and write "Services.msc" to open... well services
2.- Search "Bluetooth Audio Gateway Service"
3.-Double clic it and on the Startup type select disabled. If the service is running you can stop it.
Now read that most likely you will loose some functionality like the battery level on your device, but if you are like me you onyl use you headphones for audio and have an extra microphone (like the one in the laptop).
And no, there's no human way to use microphone and have good audio quality on the same headset on windows.
edit:instead of "uninstalling drivers (for all the hands free options and the device itself)" you should have disabled them, windows detects devices without installed drivers and installs them, that;s the reason why they came back.