PWM dimmed led floor lamp: can it cause eye strain?
If the frequency is low and the lumen intensity is 250 lumen/m² which is typical for TV's and monitors then yes.  But prudent designers use a PWM rate higher than the eye can respond which is about 10ms for staring and 1ms for eye or target light motion with peripheral vision. (Cadillac made the mistake on 1st invention of PWM brake lights using 500Hz which is undetectable when staring at, but moving car and or roving eye can detect the flicker, but not really a eye strain, just a threshold of eye response.)

However your camera shutter rate is faster than the eye, so it may not be proof of a frequency and intensity product that causes eye strain.

Basically excessive lumen/m² direct into the eye causes the greatest eye strain when the background is relatively dim. Which is why many bar TV's have perimeter LEDs to allow the eye iris to constrict light coming in. The glare of the perimeter backlights actually helps the eye adjust to the brightness of the big screen TV's.

This is why I always adjust my screen brightness to the minimum tolerable level to avoid eyestrain when using for extended hours of viewing. That works for me.