Was tested with RU layout. In this layout, "`" key symbol is replaced with "ё" symbol.
Layouts configured in Settings are: us, ru.
So the shortcut works on us layout but stops working on switching to the next ru layout. After switching back to us it works again.
Was reported upstream: https://bugs.kde.org/show_bug.cgi?id=407703,
so first thing I'm trying to understand if it's Qt or KWin issue.
Possibly duplicate of https://bugreports.qt.io/browse/QTBUG-73090