That's a bad test. The 16 Pro Max is set to a significantly lower brightness level. You can tell because the black bars are wider, but the visible YouTube, Google Maps, and Gmail icons are the same brightness on the 16 Pro Max and the iPhone Air with PWM off.
It is disappointing when content creators do minimal/no research about something like this before highlighting it in their video.
Ultimately, most PWM tests I've seen are not indicative of the final relationship between the screen's behaviour and the user's eyes for the following reason.
Most "PWM frequency/modulation measurements" are done either with a white or otherwise uniform image displayed on the screen, in actual usage scenarios the depth of modulation varies massively based on how dark the displayed image is on each part of the screen. If you are looking at a web page with a white background the modulation is at a certain level, if you then look at a web page with a grey background the modulation will be much more intense.
This is why increasing the frequency doesn't help anyone so much and everyone keeps returning their iPhone every year because the darker areas of the screen at any given time are flickering like crazy compared to white as there is more dimming required there, and therefore the modulation HAS to deepen in those areas as PWM is the chosen method of reducing perceived brightness.
If a display has a 480hz PWM frequency, this has no bearing on whether or not a pixel will be on or off during those 480 opportunities to be on per second. For example any black parts of the displayed image will have the pixels switched off entirely, and they are part of the screen too. Any pixel in a state that isn't "off" will be fed full voltage however many times per second it takes for a human to perceive it as the correct shade, so grey/dark but not black areas of the screen will be more likely to irritate the sensory system of a PWM sensitive individual. As you are scrolling through content, this effect is constantly changing and adapting as the images displayed change.
If the new mode Apple has created to try and solve this issue does away with this variance, has a shallow pulse tied to the refresh rate of the display (represented by the faint bars we see in these videos) and reduces the brightness of any darker areas of the display by
reducing the voltage to those pixels instead giving them more off time than the lighter/white ones then we will see an effective removal of "Pulse Width Modulation", as the entire screen will flicker uniformly and this hidden problem (and cause of most people's discomfort) will be removed.
I predict that some people will still be sensitive to the pulse despite this improvement, but many others will now be able to use the new phones. The improvement will affect those who use dark modes/themes that don't have a pure black background in app/on page the most in my opinion.