So I bought that TV some weeks a go and I noticed a somewhat strange "Pixel bar" at the bottom of films and streams.
I only stream with several apps like Prime and Netflix. The bar always shows up at the bottom. So if the film is fullsize, I see it at the very bottom of the TV, when the film has black bars on the top and bottom, I see this bar at the bottom where the actual film starts.
It's not always visible but quite often. It doesn't seem that the subpixel are broken in colors but they seem to be somewhat brighter, Hard to describe.