I've spent ages on this, and I've found a fix for me. Realtek's latest audio driver version (2.82) no longer has two options that I have found solve this issue. I downloaded the previous version (2.81) which is available on their website
https://realtek-download.com/download-hd/.
Once I installed this some new options were available for my microphone. Go to Control Panel > Hardware and Sound > Sound. Then select the 'Recording' tab. Right click your microphone and select properties. Go to the 'Enhancements' tab and make sure 'Noise Suppression' and 'Acoustic Echo Cancellation' are ticked. (These were not here when I had the most recent (2.82) version.
I've found this drastically improves the issue. If I have my headphones turned up very loud some noise still seeps through but I haven't found it noticeable and the two options suppress it very well. If I am playing games or watching something when in Discord chat with friends they can't pick up the sounds.
When installing the older version of the driver, I had a bit of a problem with the installer going in a loop every time I restarted as part of the process. I have found a solution to this here:
https://www.gfisk.com/realtek-audio-driver-install-loop-windows-10/
One note is that I think that this slightly changed my microphone volume settings on the 'Levels' tab of the Microphone Properties but I was able to just change these back to a suitable level.
Another note is that the version (2.82) Does not come with Realtek HD Audio Manager, not sure if this plays a part but it's useful to have which the previous (2.81) version does.
Hope this helps!