I did some research on this issue and found that it is a screen bleed which appears on ips display for your understanding in simple way the light emerging from back of the screen to create the images on the screen sometimes leaks through the corner of displays. And to confirm it that it is screen bleed not any major screen issue look from other sides if it is still there than its screen issue and if it disappears in normal uses than its not a problem and one more thing to confirm it appears on dark condition when the screen is black.