Most tv screens don't support full rgb (from darkest black value 0 - brightest white value 255) via hdmi and only show limited rgb (16-235) or ycbcr. Your pc will provide a full rgp image, as pc monitors can display this. The result is, that all dark information from 0-15 are bunched together on the tv to BLACK and you can only Differentiate e. G. Shadows from value 16 upwards. As an example, if you are in a very dark cave or room where most image information is in the area of 0-25 or something, you will mostly see a very dark, black image of the scene. Increasing the brightness of the tv will only change these blackish pictures into greyish pictures,but it will add the missing information. In order to chnage this, you need to go into the graphics card settinga in your pc and change the output from RGB to RGB LIMITED or YcBCr. For nvidia this ia in the nvidia control panel under resolution settings.

Give it a try, for me this solved the issue, which is by the way called black crush.

Check this out https://youtu.be/gRwK3hccv1I