There is some interesting stuff I stumble upon today. It is regarding font smoothing.
Mojave seems to change default subpixel antialiasing to grayscale. I had trouble to read such fonts on external screen. I mostly work with code in Intellij IDEs, and the fonts are really hard to read (especially on a light theme)
Frankly, I believe something is fundamentally broken my macOS applications:
- There is setting to disable font smoothing in Preferences-> General
- There is setting in Intellij IDE for font smoothing

leaving both ON (and this is by default) - results in blurry text, that takes me time to focus on:
img - broken AA, default
Disabling one of these setting (no matter, system setting or Intellij) results in much crisper text:
img - after - fix
You may try to experiment with this font smoothing, trying different options:
http://osxdaily.com/2018/09/26/fix-blurry-thin-fonts-text-macos-mojave/
For me, legacy subpixel AA is the best: you need to disable font smoothing in macOS preferences, and put the following command in terminal:
defaults write -g CGFontRenderingFontSmoothingDisabled -bool NO
Changes will be visible after restart (or log-out/log-in)
Please post your experiences with different options.
PS:
Generally I started to notice that overall font size and contrast is much smaller than I had on Windows or Ubuntu.
I'm using 23" 4k screens with 200% scaling, and everything is just too small comparing to my windows setup.
On the left - font that I can read without eye strain, on the right - default macOS font size:
comparing default fonts to comfortable
I don't know how to measure size properly, but this is around 8px height.
All the menus are using this size.
Here is another example: tab font is 6px(!) (notice contrast ratio on inactive tabs, it makes text near impossible to read):

The point of this screenshot is that the height of non-capital letters is 6px. Imagine reading non-contrast books that has such a small font for a day. Even healthy eyes will notice discomfort. And we are using macOS entire day, for 12-14 hours.
As a workaround may be getting 27-inch screen instead of 23-inch (27" is what entire Apple HQ should be using all days).
I also did a few tests/days with and without the external screen. And working on a laptop screen didn't cause such eye strain as an external screen.
P.P.S:
Going to the topic of discussion - screen dithering, again, I do not really believe in this dithering (if it was any, Iphone 240FPS camera should capture it - as the refresh rate of screen is 60HZ). I'm pretty confident that eye strain is caused by small/blurry fonts and an overall lack of macOS UI contrast. At least for my case.