whystrainwhy I think there's something in the OS itself happening for me
Yep for me I have the sensitivity to the OS/driver-related issues too. I can't even use a 15-inch late 2008 or 13-inch mid-2009 MBP LOL — even with the old dither disable methods like NVInject kext… Arguably the 2009 has super intense strobe PWM, but the late 2008 15" is flicker-free to my camera and also gives me a similar kind of brain fog feeling.
The issues are the worst on both in macOS, however even with an old Ubuntu version they still aren't usable for more than ~30 minutes for me.
I can't use the Mid-2015 15" Retina for >30mins either, no matter if I'm in AMD or Intel graphics mode.
The only exception is Late 2016 13" MBP, which is "semi" usable for some kinds of more visual tasks (e.g. photo editing or graphic design — it was OK enough to be the computer I originally learned graphic design on), but I still have that strain feeling in the background, and I can't comfortably work with text documents on it… even though I technically can use it, there's still something really weird going on.
With the 2016, the moment I need to start writing a longer document, even in the years before I knew I had LED strain I used to immediately switch to an old Windows laptop instead LOL…
(Weirdly, installing Windows or Linux on the Late 2016 MBP makes it entirely unusable, especially Linux which gave the strongest eye strain I had in a while immediately after booting it up — making it the only Mac that's actually better with macOS compared to other OSes…)
I don't have any good external monitor yet, but I've noticed that all my external monitors are worse than usual whenever they're connected to a macOS device.
Today, the only way I can "seriously" use macOS — as in, entire days of work with tons of text while consistently avoiding strain — is through a NoMachine stream via a known-good Windows laptop (AUO TN laptop LCD from 2015 with Intel drivers disabled)
For reference, I'm also sensitive to the Windows Intel driver issues that have been discussed all the way back with driver version 9 in 2012… some laptops are still "okayish" with drivers on, but the only way I can get a "TRULY/consistently" good screen that works every day is with MS Basic Display Adapter (+ a good panel of course)