I have an item delegate derived from QStyledItemDelegate, which draws a QPushButton. It is drawn using:
{{
QApplication::style()->drawControl(QStyle::CE_PushButton, &button, painter);
}}

This works correctly on Mac using Qt 5.9.6 and on Windows.

On Mac using Qt 5.11.2 the button is misplaced. It looks like some offset is added to the button.

Similar behaviour can be observed when drawing a combo box.