I bought the 8K QE85QN900B QLED tv at the end of August. It was delivered and set up a month later.

Everything seemed good at first bit now when I watch stuff on streaming (Disney+)and on 4K player the image is grainy. The occasional film (Avengers: Endgame) looks fantastic. Yet a lot of the stuff I watch has a grainy look to it. 

I've fiddled with the settings. I've changed HDMI cables. I've gone back to factory settings. I've switched off intelligent mode, played with sharpness.

Even with the last Star Wars film (Rise of Skywalker) on 4K its got a grainy picture quality to it. This is on both a 4K player and Disney+ via streaming. It shouldn't look this bad, should it?

It could be this was always there when I got the TV.

Even when I watch animation shows which are HD still look really bad with a grainy quality quite evident in the background. 

Gaming is fine. Normal TV looks fibe but I do not use very much.

Is there something to fix this or is it faulty because its such a high powered TV that it can upgrade stuff and its therefore making things look worse?

Is there a fix for this?