Microphone issues

[Motherboards]

I tried playing this game with a friend while in a Discord call, and as soon as we joined the same game, everything on my computer (the game, system sounds, and Discord) would become much louder, and I would hear my own microphone output in my headset.
I've tried changing the in-game chat volume to 0% and from push-to-talk to never, as well as changed which mic the game should access in system settings, but the problem persists, and it is VERY annoying. Any help would be appreciated.