Its possible that they limit SDR brightness levels so pixel burn in is less likely to occur. The biggest killer of OLED displays is BRIGHTNESS wearing out each of the rgb pixels.... You might have to enable windows hdr and 10bit color along side full dynamic range to properly test the monitor.

I have actually foreseen oleds coming to market in "medium" sized panels end of this year early next which will limit SDR brightness so "morons" dont run max brightness and wear out their monitor prematurely. Considering yall tested for color accuracy, you should KNOW the sweet spot is 120 nits, thus having a cap of slightly less than 400 is NOT an issue. As HDR content is controlled by the content NOT your own brightness settings. Every HDR monitor ive had, the movie or game controls the brightness NOT the monitor settings.... Adjusting brightness with a movie paused may work, but once the movie continues to play the brightness would change based on the scene.... So you are only changing SDR brightness which also tells me you only tested SDR color accuracy, probably why you got such horrible contrast ratios.

You talk about backligting but there is none on OLED panels...

Following up on this, you can measure the effective real-world contrast ratio (as memory serves me, this is around 8000:1 or greater for OLED in a dark room) and some setting they selected set the black point to gray. My gut tells me the reviewer had the color settings incorrect in the graphics driver, where full RGB was instead set to limited RGB. Doing that would limit computer's black levels to stop at a level of 16 instead of 0 out of 255, which would make all blacks to be set to no lower than 16. Presenting a 16 to a display expecting 0 as black would mean the display would output gray at best at its darkest. NotebookCheck, this might be your problem.

NotebookCheck, the issue is with your settings, so take the time to actually investigate this thoroughly instead of meeting a deadline. I confirmed this with Pepper Jobs, which would explain why ETA Prime and TheRelaxingEnd's units do not exhibit this very oblivious 300:1 contrast ratio issue.

youtube. com/watch?v=7DRNBC2UXeg

youtube. com/watch?v=MeuyOHiRht0

So does this have two or three subpixels per pixel? Hard to tell with that arrangement.