One Piece never "fell off" imo, pre ts had its ups and downs just as post has them so for me the quality has always been pretty consistent overall. The only thing pre has over post is that it's a completed work, I have no doubts that'll change when the series wraps up tho

def has a lot to do with the weekly experience, like spending 1yr of real time in Punk Hazard vs a couple binge sessions is different yk. I experienced the whole series in binges so I never got that ig, it only got better for me as I went on tbh