But for real: The biggest disappointment of them all has to be Toki.
I still kept waiting for more to happen, but that was it, Oda?
THAT WAS IT FFS?
You introduce a character from the void century with that much hype in advance and then you only let her mention her void century ties once (!) while also writing her the same boring way you write 99% of your female characters?
That's some bullshit not even the hardest homers can defend.
She served ZERO purpose. This entire travelling through time nonsense didn't serve any purpose either. Wano could've happened exactly like it did without Toki or any kind of timeskip.
Momo is a bit older (13 or 14 for end of arc purposes), Kaido invaded the country a few months ago (or maybe a year), installed Orochi, Scabbards faked their death and went hiding, while Momo, Kinemon etc. escaped on boat just like they did.
Et voila - literally nothing important changes for the story. Toki was completely redundant from the get-go.