I tried going to Control Panel > Hardware and Sound > Power Options > Change plan settings > Change advanced power settings and expanding the Display drop down located there. There's no option for auto-brightness or anything, just an option for how long to wait before turning the display off.
I also haven't been able to find any auto-brightness related settings in the Display category of Settings. I also searched using the search bar of Settings for "brightness" and didn't find anything.
Yet my computer is automatically adjusting brightness, I believe based off what's currently displayed on my screen or something. This only started happening after this most recent update. Anyone know how to disable this?