Gnome was built on GTK and GObject, libraries that have always had well defined licensing. KDE was built on Qt, a framework that did not always have the licens

Gnome was built on GTK and GObject, libraries that have always had well defined licensing. KDE was built on Qt, a framework that did not always have the licensing it has today. GTK and GObject are C libraries, and many constructs are easy to reason about. Qt is C++ based and there is a LOT going on and the meta compiler is insane.