As as observation, i've noticed straight away that Natural Mode adjusts almost instantly from/to a brighter scene/frame change, as a almost similar bright white flash. This is less disconcerting though. Turning on Standard Mode stops this, but then introduces the chance if random white flashes.
Adjusting the Picture Expert Settings doesn't help, or mitigate this change.
This random, camera like, flash in Standard Mode though, happens after a frame/scene change and interupts and flashes over the next scene. This is very disconcerting.
It seems to do it in blocks of solid colour of part of the picture too sometimes.
I assume it is a Samsung picture algorithm/processing design.
Over the years i have seen different ways of tvs handling contrast variations in picture output. Some constantly adjust the contrast, but the the picture brightness is going up and down all the while.
I had a Philips CRT once and if the top/bottom part of the picture was a strip of bright white, it would constantly make the whole screen flash bright white on and off like an SOS flashlight. I managed to turn this off though by turning down the Contrast. I lost a bit of brightness in the picture.
There is a firmware release for the MU7000 version 1240.7, I too was duped by Samsung themselves to update my TV to 1230 to try and fix an issue I have with the screen blacking out for a second or two every now and then (Which I have been trying to get Samsung to sort) but that is another story. To my surprise only to find a few days later they pulled it off the site because it wasnt working with certain features that firmware. Those who are brave enough to update to the firmware which was released today for the MU7000 and possibly other models. What this update does I have no idea as it doesnt list the fixes or improvements, think you can get them from the US site maybe. But by going by Samsungs previous attempts I doubt it will fix or improve anything anyway.
My 55MU7000 has also suffered these flashes from new and now has an additional issue with random black screens which appear on 4k HDR sources for 1 second which Samsung dont seem to know how to fix.
Most certainly wont be buying another Samsung TV after the countless issues ive had with this one & what seems other models.
Just been trying Dynamic Mode with Auto Motion Off and saw White Flash.
Trying Natural Mode next.
Also, any adjustments made in Dynamic Mode, transfer to HDR Mode too.
My 49MU6400 does this as well on 4K sources through HDMI.
I had the screen replaced not long after I got it due to light bleed but the replacement screen is now worse than the original one. It looks like two spotlights shining on the left and right hand sides.
More recently Samsung has replaced the mainboard due to this issue, but it stills persists! It's only started recently, but the replacement mainboard hasn't fixed it.
Very disappointed overall with the TV. I've never seen backlight bleed like this on anything.