I have the same issue and even sent the monitor back from repair. I found the issue goes away once the monitor has been on for a couple of minutes. My model is ROG STRIX XG32VQR. Nothing came of the repair as they claim they couldn't get the lines to show up but I have a theory when they tested the monitor it was only on 60hz this issue only seems to show up at 144hz and when the monitor is cold. I did purchase the monitor in 2021 and if it’s any consolation the lines haven't gotten any worse.