Who is responsible for the fact that the Icons in the Plasma/Kickoff Menu have become Monochrome.
And how can I return them to color?
In the “Edit Menu” Window they are colored.
And changing the theme and other view settings from the GUI does not help
Its a recent change made in KDE. Changing your theme can work but only if the author use colored icons instead.
So look for a new theme that do that or fork and edit yourself all the icons you dislike.
I wrote in kde bug, I wonder if they will answer 
