Wrong color on titlebar/toolbars with setUnifiedTitleAndToolBarOnMac(true)

When using

setUnifiedTitleAndToolBarOnMac(true);

which is used, for example, in the "Qt Widgets - Application Example" in Qt Creator, Qt tries to mimic the native titlebar and toolbars of macOS. However, the colors of the titlebar/toolbars don't match the native colors (see attached screenshots).

Qt's color focused window: #d4d4d4
Qt's color unfocused window: #f6f6f6

Native color focused window: #ffffff
Native color unfocused window: #ececec