AGI I have tested with 2 HP laptops - one from 2014 and the other 2018 model. Both give the same results. I will be testing with older devices sometime later and will update you about the results.
I think it is important to note that I am also testing my new phone Hisense A2 pro, which also gives me some kind of tension in the head. I am not sure why, because the response rate seems the same as on my yotaphone 2 eink side, which is perfect. The only difference between yota and hisense is that hisense is built with glare screen and the yota - plastic. Yota looks like picture or caricature, toy phone (as many people said to me) and the hisense feels more like real phone - just black and white. And yeah, on yota I was using a lot of black backgrounds and hisense is mostly white everywhere.
I think the problem might not be the refresh rate or flickering, since I cannot read books anymore too. I think I might became intolerant to high contrast or bright white in general. OR maybe my eyes got weaker and I need vision therapy, thus I found one of the best oftalmologist in the country and will ask to do in depth testing of convergence, suppression and everything else mentioned on this forum. Also I ordered pack of IRLEN overlays, which should help if my problem is contrast. Will update on this too.