Sorry nothing else comes to mind off hand.
Assuming that you have the latest video adapter driver installed, you've not messed with adaptive brightness nor the "night light" feature. I can't think of anything else except perhaps rebuilding your icon cache and thumbnail database and see if that has any impact
http://www.thewindowsclub.com/rebuild-icon-clear-thumbnail-cache-windows-10
There's a small file at the bottom of that article that makes the process automated, you might want to try that "Thumbnail and Icon Cache Rebuilder"
There used to be a slider in settings to adjust the brightness but evidently they've deprecated that.
Some laptops have a function key that you can employ to brighten or dim the screen, if your computer is a laptop.
There are some advanced system properties settings under performance which you might want to look at and see if anything there looks unusual
The image above reflects my settings and my desktop icons appear OK.