How to disable Mojave’s desktop tinting (with reduce transparency)?
Set your Desktop background color to pure white:


  System Preferences > Desktop &amp; Screen Saver > Desktop > Colors > Custom Color… > Color Palettes > White (double click)


Even in the “Reduce Transparency” mode, Mojave calculates background colors off the desktop wallpaper, so having white there ensures light backgrounds. The contrast with text is much better.

Also, the setting “Increase contrast” in Accessibility &gt; Display gives the best contrast, but it adds black edges to UI elements.