Wallpapers don't look good even when using my monitor resolution

So, I've been having an issue lately with my computer that's making wallpapers look kind of "bad quality"

My monitor is 1920x1080, 16:9 and I'm using 1080p wallpapers, and they have a sort of grainyness to them, like little dots on the edges of objects in the wallpaper.

I wanna get this sorted so I can have some crisp wallpapers.