Here's the video, so you can see what I'm talking about. Basically, XPS 13 9360 QHD, has this issue when in a dimly light room, the brightness will be automatically set to the max, and won't be changed by either bios settings (you can adjust brightness level there for battery/AC), latest driver settings, or by keyboard keys.
It'd work normally, but then it'd start going bonkers, but then it'd go back to functioning normal.
Or just stay at max brightness.
I tried disabling DBC, installing latest graphics driver from Dell website, or Intel website using this method, installing latest bios, and other recommended drivers, disabling sensor monitoring service in "services.msc", didn't help.
If you go into the power settings, can you disable it there for both AC and Battery? Just wanted to make sure that was checked too.
Yes I did that too, also just an update. The problem went away.
Can't say for sure that it's due to my updating graphics driver from Dell website, since the issue didn't go away immediately (yes, I did restart OS). It only went away after a few days, but I did nothing afterwards, so the issue just went away on its own.
Well at least so far, auto/dynamic brightness haven't been observed.