Hi,
You mean this list?
http://www.wsgf.org/mgl/uwsThere are 4 Grading options.
A: Golden, Works Nativ flawless
B: Silber, minor Bugs, like stretched Hud.
C: Cooper, huge Bugs.
Unplayable: Black Bars or similar.
Sadly Payday 2 does Not yet have a Detailed Report.
But for BattleField4 it states Golden 21:9 Support, and if you look at the Screenshots there you can see a clear Hor+ behaviour from 16:9 to 21:9.
http://www.wsgf.org/dr/battlefield-4/enDoom is a perfect example for a Silver Grading.
http://www.wsgf.org/dr/doom-2016/enYou still have a good Hor+ Picture but as you can read in the description there are minor blemishes with the weapon.
If your computer does not behave the same as in the Detailed Reports then there seems to be something wrong.
Maybe if you could provide a few Screenshots of the games you mention in your Native 21:9 resolution and then in 16:9 we could see what kind of problem you have.
Also, do you play games in the same resolution as your desktop resolution? This often can cause problems if they are not the same.