i didnt even bother to read page 2, um... games have banding, videos have banding, everything has banding, that is how the math works: if you have a very small change gradient, such as grey 20 to grey 30 (8bit max capable of 255), then you only have 10 steps of brightness that you can store & display, but your screen is more than 10 pixels in dimensions, therefore there will be banding guaranteed
to make banding less ugly, you need dithering, some images do this, some games do this, some videos do this on their source, but many dont...
do not post bad quality photos of your monitor UNLESS you also post a screenshot of that same moment in time for everyone else to view the same image on their own monitor to confirm
videos come with additional issues like blocking, so instead of an organic looking puddle band like on that witcher image, you might see large squares because video compression is designed to be based on human vision, meaning darker colors or small gradients (like an image of the sky) & the differences throughout them are harder to notice, therefore it is a waste of bandwidth to store such colors at high accuracy compared to lighter colors & detailed objects (you may have also noticed, colors like red/green/blue look like they are quarter resolution, this is intentional, human vision perceives contrast more than color, so most jpeg/video compression stores colors in half or quarter resolution compared to brightness in full resolution)
do not think videos will ever look good unless they are extremely high bitrate (50+), i have seen official hollywood blurays with messed up artifacts on a company logo, you are almost always going to be viewing lossy compression, accept it or add post processing to your video player (drivers can also 'enhance'), but i personally dont want to alter the existing quality since it may result in losing details somewhere else
speaking of screenshots, open it in a photo editor or any tool that has an eyedropper, zoom in, now click & drag around on the blocks/spots, hopefully your tool updates the color in realtime while you drag, if you then see that the color does not change in the photo editor, then that means that block is exactly like that as rendered BEFORE it reaches your monitor