QStyle::drawItemPixmap() basically does the same as QIcon::paint() except that it does not need to retrieve a QPixmap from the QIcon first.
Currently there is a mix of both versions in the styles available but I suggest to replace QStyle::drawItemPixmap() with QIcon::paint() as this avoids e.g. the knowledge about the current dpr, also QStyle::drawItemPixmap() refers to QGuiApplication::layoutDirection() whereas QIcon::paint() is using the layout direction from the paint device which may differ.