- Edited
Welcome!
Unfortunately, what is causing symptoms is difficult and at the moment, seems to be varying among people.
Have you checked to see if the windows or mac computer flicker at all? A common trick is with a video camera. Isolating problematic stuff is important.
Personally, I stayed away from potential symptomatic devices until symptoms cleared, then individually checked them for flickering with a camera and whether I started to get headaches or not (they generally happen within a minute or so for me).
To disable the hw overlay + force gpu rendering really helped me alot with my galaxy s5
I wonder what changed by forcing gpu rendering. Did it stop dithering?