Faint line only visible on certain shades of grey

[asdfguy]

So I have a Dell S2415H glossy IPS display, and when I display a medium grey image, there is a very faint line that shows up. this does not happen with any other colour, like black, white, red, green, blue, etc.

What could this be? I changed the HDMI cable with the same issue. I even tried it hooking it up to my MacBook Pro with the same problem.

Any suggestions?



Here is the image where I used to paint to show white, grey and black.

 

[asdfguy]

I had the monitor for 4 years now. But I haven’t used it for an year. I have been using my Iiyama 4k Monitor. So this was just collecting dust. It’s the first time I powered it on since April 2022. I tried leaving a white image for a while and checked it again with no result. I even turned it off and powered it back on after one hour with no fix.