I think for this flashback, the problem is Oda's estimation for how long it would take to finish it not lining up with how long it actually took.
For example, the mountain god scenario was basically a chapter and a half affair. That sequence basically allowed time for Kin'emon and Denjiro to receive some foundation to their characters and devotion to Oden. Something the other retainers don't get nearly as much. It's like at some point in the process, Oda realized this flashback was running for a lot longer than he envisioned, and needs to get through all the stages of Oden's life as quickly as possible. Whitebeard and Roger taking up the most chunk as Oda concluded those beats were the most important. And in a sense, they were, for the greater narrative of the series. However, he neglected the Wano centric pieces that form the emotional core of the arc's plot.
We need to care for the people of Wano for the country's liberation to matter. We need to care for the Scabbards as their mission is to carry on their lords' wishes. We need to care about Momonosuke living up to his father. We need to care about Hiyori suffering for 20 years without her family. We need to hate Orochi for lying and betraying Oden and the Kozuki. We need to both hate and fear Kaido for his rule and strength. However, in an attempt to go through the flashback as fast as possible, some of these authorial intentions are either not communicated as strongly. Either due to contrived plotting or lack of proper investment.
We get very little inclination of Oden's and Momonosuke's relationship, for example of little investment. And Oda is clearly building towards Oden's big agreement with Orochi/Kaido to be of a tragic, noble nature, but the mounting circumstances surrounding it make whatever deal he made very tough to swallow, and you come out with the sense all of these horrible things came about due to PIS.
I'm still gonna reserve my final judgement until we ultimately learn why he agreed to let Orochi and Kaido off so easily, but things are not looking good.
If it all goes belly up, it doesn't reflect well on the rest of the arc if Oda doesn't stick the landing. He's put all his cards on this Oden/Kozuki storyline carrying the arc, sacrificing development and focus of many other players in the arc to flesh it out. Next chapter is likely the most crucial chapter of Wano yet.