Darius New Patch Changed 5.20

The patch notes mention a nerf in the slow caused by Darius's W. It said the value would be changed from 90% to 40%. However the in game tooltip of the ability it still says 90% slow and behaves almost exactly the same. I do not notice a change in the slow. It does not seem as if this change was actually implemented. It could just be that the champ is already slow and I slow him enough it seems like 40% but I am not sure.