`Qt::AA_UseHighDpiPixmaps` is enabled by default in Qt6

kcms/colors/editor/kcolorschemeeditor.cpp

@@ -16,7 +16,9 @@
 int main(int argc, char *argv[])
 {
     // Fixes blurry icons with fractional scaling
+#if QT_VERSION < QT_VERSION_CHECK(6, 0, 0)
     QGuiApplication::setAttribute(Qt::AA_UseHighDpiPixmaps);
+#endif
     QApplication app(argc, argv);
 
     KAboutData aboutData(QStringLiteral("kcolorschemeeditor"),