Excessive Reverb/Audio Doubling [Gameplay][Client]

The sound in the game has suddenly gone to crap and a half, sounds like I'm hearing it through a bucket with a speaker strapped inside instead of through high-quality headphones. Happens both in the client and the game itself. I've tried everything I can think of to fix it with no luck, and the wife is having the same issue too.

-Reinstalled audio drivers -Tried headphones and speakers -Checked both League and Windows audio settings -Good ol' fashioned unplug and plug it back in

And I know it's not both mine and the wife's headphones and speakers simultaneously going bad by some freak stroke of bad luck. Everything else sounds perfectly fine through both. Other games, Youtube, music, generic Windows noises...

The only thing I can possibly think of as a cause is a recent Windows update. Both of us hate the annoying af update notifications and hard blocked (regedit, GPedit, the works) all Windows updates entirely, so we haven't gone through one in a very long time. We both recently got a free 3 month membership to the PC version of the Xbox Game Pass, and enabling the Xbox app came with a 100% mandatory update. IIRC I went from build 1706 to whatever the current is (1909?). That was on Saturday, just now playing League again. Sounds before that were perfectly fine.