QScreen wrong geometry when rotate left then normal

KDEBUG-356228 https://bugs.kde.org/show_bug.cgi?id=356228

When rotated 90 degrees then rotated back again by kcmshell5 kcm_kscreen, the plasma-workspace' DesktopView rendered strange geometry, shown as below:

https://pbs.twimg.com/media/CVWLgUPUsAA9X1Q.png

https://pbs.twimg.com/media/CVWLfOPVAAAyH65.jpg

https://pbs.twimg.com/media/CVR8VSnUEAAK8cR.png

but use xrandr it is ok!
xrandr --output LVDS1 --rotate left
xrandr --output LVDS1 --rotate normal

the plasma-workspace was able to render correct geometry as the current resolution mode size.

Because plasma-workspace's DesktopView use QScreen https://github.com/KDE/plasma-workspace/blob/master/shell/desktopview.cpp#L38

and converted libkscreen's OutputPtr to QScreen https://github.com/KDE/plasma-workspace/blob/master/shell/shellcorona.cpp#L926

so it might be QTBUG, please someone point out my fault if any, thanks a lot!

Regards,
Leslie Zhai