andc i suspect that notebookcheck pwm reviews are highly untrustworthy.
i have read several reviews that dont match.
Also my Xperia XZ 2, in notebookcheck, says it has pwm until 28%. But i check that it has also beyond that point almost until 100% with my canon 550D at 1/4000. I also use a 1.4 aperture lens, so i can i have light to check it.
Above the 28% brightness what happens is that the phone seems to go to a higher pwm frequency.
Until 28% is 2khz, above that seems to double it.
I am waiting for my oscilloscope to arrive to check it properly.
So maybe some displays, change PWM frequency depending on brightness.