I can stand my macbook pro 2017 one hour max.
And keep following this forum to figure out where's the problem.
It's not PWM:
100% of brightness does not solve the issue.
It's not the blue light:
Working under the bright sun outdoor or blocking blue light via apps or glasses does not help.
Font smoothing is turned off,
matte screen protector is applied,
resolution and bit depth are lovered by SwitchResX,
touchbar is off and taped,
keyboard backlit is off.
Intel/Radeon switch changes nothing.
Color profiles change nothing.
Sierra, high sierra, mojave change nothing.
What is left?
PS
When connected to external Dell U2716D (USB-C to mini DP dongle) — all symptoms are gone.
With windows laptops I have some strain, but different kind and not as bad.
With old computers of any kind have no problems at all.