The transition to Chapter 4 - 5.
This is quite short, but I really didn't like how chapter 4 was this really serious chapter that had developed Susie and Ralsei's relationship as a team, but then Chapter 5 completely throws it all down the drain. I found the transition incredibly jarring and bizzare, I was incredibly pumped for how chapter 5 would top off chapter 4 in the lore drops, but I guess it couldn't top the reveal of the damn prophecies. Toby had no right to make chapter 5 as fun and whimsical as it was, it should've been chapter 3 instead.
I also hate how the festival was set up as this big event that would most likely be traumatic for even the heaviest of fans, yet it doesn't even last most the chapter. Imagine a chapter set in the Light World, I would've just made the festival chapter 6 or 7, the Roaring Knight comes out to the public eye, before corrupting the Lighg World with titans etc.