- Edited
So I've had some time today to test if dithering was the issue for me, and it doesn't seem like it. I'm still getting eyestrain. So I'm just going to assume my eyes need to adjust to the new font rendering.
When you get a new prescription of eyeglasses is the only way I can describe this eyestrain phenomenon. Everything is more clear, but your eyes strain for the first few days.
One thing I did was download Redshift to adjust the color temperature to something really warm like 4500K. It does seem to take the edge off the "intensity" of the strain. Each day I'm going to increase it by 100K until I'm back at my calibrated 6500K, and hopefully by then everything will be Ok. And if not, then there must be something definitely going on differently in Linux then Windows.
EDIT: Hour and half later using Redshift, and it's been a drastic improvement in my eyestrain.