Detailed but short:

• The music is ruined (slowed down, robotic, horribly distorted) unless another sound is being play on my system (in or out of the game).
• Only happens after the first in-game sound is played. (If I just start the game and don't trigger any sound inside the game, by clicking menus for example, music plays normally.)
• Doesn't happen if the audio output is set to my screen, only on my headset. If I switch the output to the screen, it fixes the issue until I switch back to the headset and trigger an in-game sound.

The full story:
I hadn't played the game for a long time (tower starting level research was still a thing).
When I launched the game yesterday, I was in a voice channel on Discord, everything seemed to work fine at first, but at some point the sound of both the game and Discord was ruined. I thought something went wrong in Discord so I tried leaving and joining the voice channel, then restarting Discord. I restarted the game, changed it from full screen to windowed. Tried a Youtube video, noticed the sound was also ruined if the game was running. Restated my whole PC...
I noticed something weird, when I was trying to toggle options in settings to see if it was cause by some experimental stuff: when I spam clicked an option - any option - to toggle it, the music was working normally. I enabled debug mode and it's like as soon as sounds are at 0/48, music starts bugging.
My friends asked me what was going on, so I joined the voice chat again to explain and.... the sound went back to normal! (most of the time - I could still hear it glitching for a tiny moment once in a while.)
I updated my video and sound drivers using Nvidia GeForce Experience, I used Windows Update and restarted multiple times until it told me everything was up to date and updated my headset driver using the Omen app. That didn't fix the issue. I play other games and never had such an issue before.
Now, I can't play Infinitode 2 without having distorted music... unless another sound is being played. Music is a huge part of what makes me keep playing one more game.