ensete That would indicate that flicker is not your issue at all, but a sensitivity to color. My symptoms are the same. The "technical" term for this is Irlen Syndrom. Green is a very common color filter used, it is also used in Migralenses, a colored lenses used to help folks with migraines.
An interesting observation for myself to make, I had commented the other week that I found the Windows protanopia colour filter somewhat comfortable to use at times. I'm not colourblind, but it makes things look a bit less saturated and thus less dazzling/more comfortable for me. So, I had my monitor in RGB mode (w/o filter) probably for the past week and was finding colours to be more intense than I prefer. After looking in my Intel drivers for a saturation slider (there isn't one on mine) I noticed that one reason I probably like YCbCr 4:4:4 mode more instead is because it's very slightly less saturated than RGB mode on my setup.
I have been finding traffic lights and vehicle led lights at night a little annoying lately because they are too "rich" in colour. Also quite a lot of after-imaging from looking at white text on a black background which also appears as dark lines on a monitor screen and I didn't notice this as much before in the past so something is changing.
So, back to green. When I was dealing with visual migraines, I would put Windows into greyscale colour filter mode (which can be toggled on/off with a hotkey once selected) and on my monitor's preset setting I would set R to 0 and B to 0 and G to 100 (the max, 255 on some other monitors). And this would somewhat approximate a monochrome green phosphor monitor since it is only a single pixel being lit up that is already mixed for monochrome mode and it would feel more comfortable at times.
For monitors that don't have menu setting that lets you set the R G B (esp laptop displays), you can do the same thing with the graphics driver control panel.. you just move the R and B sliders to 0 and leave G maxed. Again, remember to activate the greyscale colour filter.