I have an alternative explanation for everyone to consider. I keep a lot of my old hardware for spares, backups and the like. Its fairly common for me to return to an older device and find it causes me symptoms when previously it was fine. I do not believe the hardware has changed, but I know I have. My eyes and brain are getting older, whatever defect causes me these symptoms has either worsened, or my brain is less able to adapt to it. When I was a teenager I could recover from a bad migraine in hours, now in my thirties it takes days. Its a normal part of aging, the older you are, the longer it takes you to learn and for your brain to adapt and recover. Perhaps when you were younger, your brain could adapt to your GPU before you experienced symptoms.
I know this opinion will be unpopular with many here, but it underpins how I treat my own problems. Knowing the problem is within me, I don't look for the problems with devices and software to fix. I instead consider, what can I do to help myself adapt to this device. Exercise stimulates the growth of new brain cells, so when I need to try to adapt to a new phone, I sit on an exercise bike whilst using it. previously it used to take me 6months of suffering to be able to use new phones without headaches and migraines. Now, with my exercise bike trick it takes me just a few weeks and much less pain.
I found what I eat can have a big impact on my symptoms and health in general. Through trial and error I found that my body really doesn't like red meat, diary and other more specific things. I cut those things out of my diet many years ago and found that my screen intolerances stopped worsening. Infact, for the last three years my screen intolerance has actually been improving. I am hopeful that in another few years I will no longer have any issues with screens at all.
So my advice for you, and everyone else. Focus your attention on yourselves, not the tech, and see how it works out. See specialists in eye health, see what you can do to improve your brain health, look at your diet.