I think people are exaggerating the drop rates or are just getting bad RNG. I was pulling for I think 2 hours or so in loping the other day and was slowly getting more ZP than I was using.
I actually think it's the opposite. Those two hours aren't real indicative of the drop rate changes. In the 4 days since nerf they have been roughly as rare as any other drop. I have no idea how many mobs are in loping planes but HoH or qvic seem to be about 1 in 3 or 4 clears down from >1 per pull. Furthermore, there's a threshold where you go from getting more than you use to getting less than you use where even a small adjustment in drop rate can fundamentally alter their purpose... in this case we would all agree that the change pushed us over that threshold. As such, our kill rate has also plummeted so the drop rate went down and the kill rate went down and those two things compound multiplicatively.