Deepak I suspect it might have have something to do with the intensity of the flicker. Here's what I would suggest:
Using your phone camera, turn on video recording mode and bring your phone up very, very close to your new monitor. Now observe if you see or notice any light pulsing in the screen. Now, increase your monitor brightness by 25%. Then again and repeat the same steps. Continue this until you do not observe any vigorous flickering or until 100%.
I suggest you keep your monitor contrast level down as low as possible during the test. VA24DQ's max brightness of 250 nits is rather high imo. By keeping your contrast level down, the final light output is not as high.
Through your phone recording, once you have identified the brightness interval that has the least vigorous flickering, record that number down. Then, reduce the brightness level down until before the vigorous flickering resurface. Note that the brightness level. That number is the number which monitor will not trigger any sort of harsh flickering, resulting in eyestrain.
Now that you have the number, the next thing is to do something about the high brightness level.
- You could adjust the constrast level as low as where it is comfortable for you.
- If you could not go any lower with contrast level, now go to your monitor color temperature setting and reduce each Red, Green, Blue level to 80% each, for instance.
This will "trick" the monitor to maintain the high brightness to prevent the onset of harsh flickering, while in reality it is outputing lower brightness.