Global shortcuts has "Toggle Present Windows (Current desktop)' set to a key. In KDE 5.9, when that key was hit once, it would explode the view of all windows. When that key was hit again, it would jump back to the previous view In KDE 5.10.1 (and now in 5.10.2), when that key is hit once, it explodes the view of all windows. When that key is hit again, nothing happens. The only way to 'unset' the exploded view is to click a blank area of the desktop, or a window. This does not match the concept of 'toggle', IMO. The behavior in 5.9 was more in line with what is expected.
Duplicate of https://bugs.kde.org/show_bug.cgi?id=380902
I think the issue is that "Present windows" just ignores the keyboard input all along. When it's working, You can type window names and discards the ones that don't match the query. This is why I don't need a taskbar and why I assigned the Alt+tab shortcut :(. I hope the status soon changes from unconfirmed.
*** This bug has been marked as a duplicate of bug 360841 ***