Qt for Python (PySide/Shiboken)

Why do I get QApplication.style().name() == "fusion", and QIcon.themeName() == "breeze", whereas the application style is set to breeze in the KDE Settings, and the app theme is generally dark? In the Settings, icons are "breeze" indeed, not "breeze-dark". But other desktop items display bright outlines of icons, and only my app has dark icons.