Like Bug 432747, but for the Large Icons task switcher. After it loses focus or should otherwise be closed, a phantom non-interactive representation of it remains on screen.
Bug 432747 and this one seem related. I wonder if some effect went rogue. Can you check kwin support information while there is a phantom window?
What's the command for that again? I always forget. I really wish https://phabricator.kde.org/D21875 had landed. Any chance we can revisit that?
qdbus org.kde.KWin /KWin supportInformation
I can no longer reproduce this issue. If it happens again, I'll re-open and add that info.