Question Grey lines across screen

kinggaming60

Reputable
Dec 3, 2018
95
5
4,545
I've had this monitor for a while now it's the BenQ XL2430, and it only happens in csgo and has never happened before on any other monitor or game. Whenever I tab out or tab back in I will get these weird grey horizontal lines across my screen, then whilst playing the same thing will happen. It only happens in this game so I don't know why it's not happening elsewhere. any help would be amazing.
 

kinggaming60

Reputable
Dec 3, 2018
95
5
4,545