KWin tiles blurs wrong areas

[MisakaImoutoWaifu]

When you shift+drag a window (a feature of the kwin window tiling) the blur effect is applied in very incorrect areas in relation to the "window" being show.

Attached is a screenshot of the bug. The window is being dragged while shift is held, which shows you a grey area representing where the window will be if you let go. Below that grey area there is a region that should be totally transparent, yet is blurred.

Also attached is what this tile effect looks like with the default plasma blur desktop effect.

And finally the theoretical expected output

[taj-ny]

If you're using Blur all except matching, you can simply add an empty line to the window class list as a workaround for now.