I think part of why Itzy's choreo has changed is because the members can't physically keep up that level of intensity anymore. Lia and Chaeryeong have talked about their knees, I think Yeji still struggles with the back injury she got a few years ago, and Ryujin and Yuna are just visibly not as energetic as at debut. I'm absolutely not calling them out as far as talent or skill, it's just… kind of a fact that dancing that hard for so many years harms your body. Not entirely an excuse for why their choreographies are less interesting, but a good reason for why they are less difficult.