Why exactly are we calling it "Kat buff"?
Late game her ult cd doesnt really matter a lot, but having almost 1 minute more cooldown on it until level 11 is probably gonna slow down her snowballing a lot.
Not sure if its the right thing to do (Id prefer damage nerfs to E and ult so that she actually has to hit one or two daggers instead of just a few Es, ult and ignite), but it is a nerf imo.