Hello,
Context: Windows, Monitor is Philips, PHL 231P4QU. PC bought in 2016.
One day I had File Explorer open, then I opened Task Manager and it overlayed on top of it, but was smaller than it.
At that time, I noticed from the right of Task Manager was a 'leaking' semi transparent trail. As if someone pressed task manager on the darker background behind it and dragged leftwards, leaving a snail's trail behind.
I tried changing Windows to Dark mode, and I noticed the trail remained. Albeit less apparent due to white mode.
Looking closer, It wasn't from Task Manager, but most bright/ white color on a black background. For example, in File Explorer, white dashes or ghost trails of the Local Disk C/D/S/etc. bars are also apparent.
I am not entirely sure if it is affecting text as well (Giving it a slight aroundish glow).
I tried restarting the PC, updating my Nvidia drivers, and unplugged then re-plugged my cable (Monitor takes in VGA, GPU port is HDMI, so I have a vga-vga cable with a vga-to-hdmi adapter).
I asked Google Gemini, but did not come to much. It did say because the effect is shown in a screeshot, it means it's not a hardware problem, though I have no basis to believe or disbelieve its information.
I don't know how to describe this as.
This is an image showing the problem https://imgur.com/a/s7wYnyw
update: I tried disabling my GPU (Nvidia GTX 1050) from the drivers menu, but nothing changed.
update: I tried disabling services and startups, did not help.
update: My transparency was already off, and toggling it also did not change anything.