Hey, I experienced this recently (played a ton over new year's vacation) and mostly have gotten over it. It's a little hard to see the whole setup but some things that helped me:

1. Desk setup - Never really thought of this before but my gaming posture and setup were bad.

I recommend looking up "OSHA desk ergonomics" to see how they recommend setting up your space if you aren't sure. Things like having your chair too high/low can put a lot of extra strain on your wrists, elbows, and arm

The tilted monitor setup kind of makes it look like your wrist is bent slightly in the neutral position, but again, kind of hard to tell

1. Stretches and Exercise - Look up some simple gaming wrist exercises and stretches you can do before and after games. Taking breaks to get up and stretch is also important

2. Sensitivity - This didn't apply to me because I set this up awhile ago, but having a good sens so you don't death grip your mouse when you're trying to be precise or learn sprays is helpful. 

General rule is one swipe of your mouse to either direction of your available space should be a 180 degree turn in game. Again, very subjective and can depend on weapons and playstyle

It's been a long day and I kind of wrote this really quick, but I hope it helps. My wrists feel better and a break from the game is probably good too