is this a monitor problem?

[djmjmgames]

I have been searching for a answer about it in severals sites, forums and communities, but nothing them answer me.

When I bought my monitor, the videos was beautiful, 1080p was running fine. However, a time ago I have see that the image got worse, in the same conditions, same videos, same 1080p. Now it seems lower resolution, but is 1080p still. Pixels and squares appear where before was a quality image.

Is this a monitor problem? What can cause it?

 

[Lutfij]

You may want to uninstall and reinstall your GPU drivers. Might it be possible to list your full system's specs? It'd be best if you could list them like so:
CPU:
Motherboard:
Ram:
SSD/HDD:
GPU:
PSU:
Chassis:
OS:

Your post makes no mention if it's a desktop or a laptop powering an external/secondary monitor.