This is an upstream of KDE bug https://bugs.kde.org/show_bug.cgi?id=365864
When one has e.g. a QQuickView embedded into a QWidget based application the embedded view is not adjusted correctly in the sub-surface protocol. To reproduce:
1. Start a Wayland compositor (problem verified with Weston and KWin)
2. Open systemsettings5 on platform wayland
3. Go to "Display and Monitor"
4. ensure there is a vertical scrollbar (e.g. resize window)
5. scroll down
Actual result: the quickview is not properly moved out of the way - in case of KWin it overlaps the top, in case of Weston it overlaps the widget area.
Expected result: The embedded view is resized in ways that it does not overlap the areas (e.g. proper clipping).
Attached are screenshots for X11 as reference on how it should look (kwin_screenshot_US3411.png), KWin (kwin_wayland.png), and Weston ()