We have a problem where we end up with monochrome and color versions of icons being used inconsistently. This problem exists in our own system settings, our own application settings, our own desktop shell and 3rd party applications.
I think the best solution might be to create a specialized icon loader function for getting icons from directories marked as Scalable. Then we can use that loader in the few places where it is necessary.
[[ https://api.kde.org/frameworks/kiconthemes/html/classKIconLoader.html#af49b50de774a495fc7ef3d107db4df00 | We already have a way to classify icons as Scalable ]] and the [[ https://cgit.kde.org/breeze-icons.git/tree/autotests/scalabletest.cpp | scalable test for breeze-icons ]] already uses it, so I don't think it's impossible.
All Scalable icons for icons in the Applications context are color and are supposed to be only color, so this can work.