I guess I'm the only one who notes that he didn't eat dragon flesh when he just had the chance. I guess he thinks there is no time, but you can eat and run.
@highstream
He probably hasn't finished evolving. I think he just temporarily released his full potential, but he hasn't yet reached the point he can stay that way.
This section seemed a little rushed. It's one of those things where it's like if he can take on an S-Rank already, what is even a threat to him? Hiding his power?
I think the Author sorta jumped the gun on the rematch and having the power spike even if temporarily. But that's just my personal opinion for now, maybe I'll change my mind with later content.