It’s hard to avoid the obvious Goku Ultra Instinct jokes when he’s pretty much doing it.
This is a loooong fight. But, I get it. It’s the final battle. The last confrontation between our main protagonist and chief antagonist. It all ends with this battle, so I can see why it’s being milked for all it’s worth.
Plus, the audience has to understand why The Crawler is winning. Sure, I knew, but My Hero Vigilantes’ covered in subtlety. This is the creators’ way of making sure everyone’s on the same page. And what is that page? Quirk Evolution + Fighting Style.
We’ve seen quirk evolution in the main series several times. Aizawa getting the students past their quirk limits thought rigorous training as well as the League of Villains growing stronger from their constant battle against Gigantomachia early in My Villain Academia. The more you train your quirk, the stronger it becomes. That’s a given in this universe, and we know Koichi’s had years of illegal quirk usage, so, yeah, he’s at peak quirk performance.