QML Fusion style ignores dark theme on macOS

I'm using Qt 6.4.2 on macOS 13.2.1. To repro,

• load the 6.4.2 QML Layouts example,
• in main.cpp, add "QQuickStyle::setStyle("Fusion");" and "#include <QQuickStyle>"
• in CMakeLists.txt add QuickControls2
• Compile and run. The app style is now correctly "Fusion."

In the macOS preferences, toggle the macOS theme from light to dark. Nothing changes and the app stays light. (Note that without the style set to Fusion, this Layouts example does correctly follow the macOS light/dark setting, so something is wrong specifically with Fusion.)