Despite almost scoring 40 goals the year before, last year Zibanejad decided that he was primarily a passer. Once he decided that, he stopped pushing to get into good places to take a shot. There were plenty of times he would do that and still opt for the pass in 22-23, but his shot choice and location were still very good.
The result of deciding he was a pass first player is that he now spends almost all of his time on the perimeter. Being a shooter means you're always trying to find the best place to take your shots from and that's not the way he's playing anymore. Looking at the player from pure stats, you would never know this. His shot and shot attempt rates didn't change all that much last season compared to the year before. But if you've been watching him, you see the difference in his approach.
I'm not really sure the reason for it. It's hard to tell if his actual skating ability has taken a dip or if it's a mental thing, but what's wrong with Zibenajad is all about the way he engages (or doesn't engage) with the puck in the OZ.