tfouto Did you test the screen to make sure you are outside the PWM range? Sometimes Notebookcheck's % values are not that accurate.
Also I couldn't use such dimming apps. Whenever I did, burning eyes. They must trigger temporal dithering. But whether or not they do might depend on the device, GPU/driver.
When I think about how the Dasung shows dither when using f.lux, and various people online said changing colors or brightness (via software) might activate temporal dithering on PCs, that idea, apart from my own experiences, has some backup and might apply for Android, too.