QComboBox FramelessWindowHint not work on MacOS

[Hector_J]

Hello,
I built a QT application on macOS Big Sur, and my QT version is 6.2.0.
When I built a custom QComboBox, the drop-list always had a shadow black frame behind it.
I tried to set flags below, but it still not work on Mac system. (But it works on Windows system)

comboBox->view()->window()->setWindowFlags( Qt::Popup | Qt::FramelessWindowHint | Qt::NoDropShadowWindowHint);
comboBox->view()->window()->setAttribute(Qt::WA_TranslucentBackground);

detail code:

    comboBox->setStyleSheet("QComboBox {"
                                "combobox-popup: 0;"
                                "background: transparent;"
                                "border:2px solid red;"
                                "border-radius: 10px;"
                                "padding-left: 5px;"
                                "background-color: white;"
                                "font: bold;"
                                "font-size: 16px;"
                                "color: rgb(107,107,107);}"
                            "QComboBox::down-arrow{"
                                "image: url(:/resources/icons-chevron-text-down.png);"
                                "background-color: white;}"
                            "QComboBox::drop-down{"
                                "border:none;"
                                "subcontrol-position: top right;"
                                "subcontrol-origin: padding;"
                                "width:40px;}"
                            "QScrollBar:vertical {"
                                "border: 1px transparent rgb(213, 218, 223);"
                                "background:rgb(213, 218, 223);"
                                "border-radius: 2px;"
                                "width:6px;"
                                "margin: 2px 0px 2px 1px;}"
                            "QScrollBar::handle:vertical {"
                                "border-radius: 2px;"
                                "min-height: 0px;"
                                "background-color: rgb(131, 131, 131);}"
                            "QScrollBar::add-line:vertical {"
                                "height: 0px;"
                                "subcontrol-position: bottom;"
                                "subcontrol-origin: margin;}"
                            "QScrollBar::sub-line:vertical {"
                                "height: 0px;"
                                "subcontrol-position: top;"
                                "subcontrol-origin: margin;}");

    QListView *view = new QListView(comboBox);
    view->setStyleSheet("QListView{top: 2px;"
                            "border:1px solid red;"
                            "border-radius: 8px;"
                            "background-color: white;"
                            "show-decoration-selected: 1;"
                            "padding-left: 5px;"
                            "padding-right: 6px;"
                            "padding-top: 6px;"
                            "padding-bottom: 2px;"
                            "font: bold;"
                            "font-size: 16px;}"
                        "QListView::item{"
                            "height: 30px;"
                            "background-color: white;"
                            "color: rgb(107,107,107);}"
                        "QListView::item:hover{"
                            "background-color: green;"
                            "color: white;}");
    view->setCursor(Qt::PointingHandCursor);
    comboBox->setView(view);
    comboBox->setMaxVisibleItems(5);
    comboBox->view()->setVerticalScrollBarPolicy(Qt::ScrollBarAsNeeded);
    comboBox->setFixedSize(500,45);
    comboBox->view()->window()->setWindowFlags( Qt::Popup | Qt::FramelessWindowHint |Qt::NoDropShadowWindowHint);
    comboBox->view()->window()->setAttribute(Qt::WA_TranslucentBackground);