But this isn't "a power up", this is the 3rd power up Luffy has had fighting Kaido. Every other big enemy has been defeated.
Kaido outright confirmed that his drunk forms were his ultimate power up in 1037
By his own words, Kaido stated that pre-G5 Luffy was on par with him. This statement parallels what Linlin said to Kid/Law back in 1031
In 1031, Linlin sacrificed her lifespan to gigantify, just like how Kaido got drunk in 1037. After which, Linlin did show her ultimate move(misery), yet she had no other major power ups.
Why should kaido be any different? Even in regards to awakening, we've already seen it. Luffy is a mythical zoan, just like kaido. His awakening allowed him to:
- spread his powers to the environment
- buff up
Has kaido not shown the same things?
- transfers his flames to onigashima to lift it
- buffs himself up in drunk mode