Not sure this is related to Windows 11. Let me explain:
I am very sensitive to brightness and PWM and temporal dithering, and I have been paying attention to this for years now.
I am currently using an EliteBook 645 G10 at work on Windows 11 (Entreprise build 22631) with AMD Ryzen 5 PRO 7530U. This laptop has the worst display ever, I bet this has to do with the integrated privacy filter, it just destroys the eyes and the brain, I just can't look at it whether I activate the privacy feature or not.
However I have zero issues once I connect it to external monitors (like HP E24i G4). I also have zero issues with a desktop computer powered by Intel i7 9700 CPU and an AMD GPU connected to the same monitors and also on Windows 11 (Pro).
Sadly my personal computer is a Macbook Air M1 (with StillColor) and I get way more eye strain while using it on the same monitors. It is worse if I look directly at the integrated screen. I now want to leave Apple for this because it's been years and new products don't seem to bring solutions.
I also know that I was using an HP Zbook Firefly laptop a few years ago with an NVidia GPU, on Linux, it was a solid laptop for every tasks but I got massive eye strains. No Windows 11 here, just NVidia and Linux.
So what I know from my experience is that:
* Macbook M1 is to be avoided and probably every Apple Silicon device,
* AMD GPUs seems to be fine on Windows 11 if your monitor is correct.
If someone finds a laptop with a correct integrated screen (mate is better) and a configuration that could include an AMD GPU then I'd happy to try it.