I may be figuring out what it actually is. There are two factors: my eye prescription and the amount of contrast directly around the outline of the display, and it's easy to be fooled that a small room light is enough. I can explain.
The first issue is I definitely notice more eye strain if I use my long range glasses vs short range. But strangely, no glasses is still better than my long range glasses, which makes it clear that OVER-CORRECTION IS WORSE FOR STRAIN THAN NO CORRECTION.
The second issue is lighting immediately around the display. With my laptop, the light from the screen reflects off the keyboard (and remember when I said my new laptop monitor is easier on the eyes? well it's probably because my new laptop is SILVER (brighter) and my last laptop was RED (darker), it increases outline brightness!). My TV is so large it produces enough light to thoroughly light everything around it. But my monitor is both free-floating, small, and not flush to the curtains, meaning it can't really produce enough light to light the surrounding outline.
I was actually going back and forth pointing my phone light at the point below my monitor. The eye strain lessens soon after I point the light so the area underneath the monitor is lit.
Now what's interesting is that area isn't really super dark when I have one of my smaller lamps on, but it's still too dark anyway. The only way to really get it "bright" is with the room light on, which is way too bright. So the only reasonable way to fix this is to buy a standalone light that goes behind the monitor or on the desk under the monitor. I would want something that can light the area all around the monitor like what I see with my TV.
I DO NOT think overall lighting in the room matters that much. It is moreso the sharp contrast from the outline of the monitor to the surrounding. You only need like 1-2 feet of the area around the monitor to be lit somewhat to create more of an equalization.
One of the problems for the monitor in relation to like a phone used in darkness, is that even though both are being in used in darkness, the monitor will be far worse if there's no edge lighting since it tends to fill more of your FOV. The only way to really change monitor FOV at least in my case is to get a deeper desk which after searching online, is prohibitively expensive if i want to be picky with dimensions. Nothing really cuts it.
So what I'm going to do is find the best way to get good lighting all around the monitor. Probably a light that goes behind and maybe one below so the bottom bezel is also lit somewhat. I have some paper taped to the bottom bezel while I look for lights. These are what I'm going to test first: 1, 2, 3. There are some other cool RGB lights that are just too expensive. I will also get a new pair of glasses even better for the exact distance I use my desktop monitor at.
And that's pretty much it. I believe when it comes to preventing my eye muscle strain, it is a combination of not overcorrecting with my prescription and making sure the area immediately around the monitor bezel is well lit. As I explained, these areas are better lit for both my TV and laptop in pure darkness due to the reasons I explained above. The desktop monitor is the worst case; large FOV, lamps have trouble lighting the surrounding area. PWM is also an issue but not all PWM is created equal, as I have no issue with the PWM frequency of my laptop panel. I have also tried to disable GPU enforced dithering with the program Calibration Tools but I have yet to confirm if this makes a difference.
When it comes to the burning sensation from my 360Hz monitors, again I still think it's either the blue LED temperature or the polarization, which for those panels was horizontal. I have a post in this thread with my polarization findings for all types of displays I've tested TrantaLocked . MOST monitors seem to have vertical polarization, with some rare exceptions having horizontal or diagonal polarization.
It is still weird because I never experienced issues with surrounding contrast causing eye strain. I don't know why it's suddenly an issue.