That's part of battle, Katakuri and Doffy did the same in many ways
, it's last one remaining standing in battle. It's mostly Luffy's fault for abusing his body just to keep up with Kizaru.
I will say though that I was shocked Kizaru was so casual against FS + Snakeman's speed, he was kinda presented as a bully in that chapter. Like he was toying with Luffy, I didn't think we would see that from a Luffy and Kizaru fight at this point.