I would say the opposite. The Samsung KS TVs are generally reviewed as having better screen uniformity then the Sony's.
The only time the screen uniformity might be better on the Sony is if you're watching a movie with black bars because it has its edge lights on the side rather than bottom like the Samsung.
But every LCD you'll get clouding/dirty screen effect to a degree and a lot depends on how sensitive you are too it and how lucky you get with the panel. To avoid it you can only go OLED.
I never quite know what to believe when people complain about clouding etc on this forum. Are they expecting too much? Are they extra sensitive? Have they got an unlucky panel? Are they running with the backlight high and expecting no bleed? Most reviews with even the best LCDs state once calibrated there's no visible clouding or bleed but that's when they have the backlight set lower. In HDR there will always be bleed because it's set at its max and if people go searching for faults like using white images on black backgrounds etc of course there will see bleed.
I feel that these people will only be satisfied with an OLED and probably then they will complain about vignetting or near black banding or whatever fault they can find with the OLEDs.
In short, never trust user threads, always demo yourself. Just remember there's likely thousands of people who have bought TVs and are happy with them who will never post on here. People mostly only post when they have a problem.