Zoro CoA haki is stronger than we through. He scarred Kaido without ACoC!
In the lastest chapter Zoro obtained ACoC or CoC coating or whatever you want to call it.
We can see the crazy lightning coming off his swords.
When Zoro cut and scarred Kaido we didn't see the black lightning coming off his swords that means Zoro didn't use ACoC at the time.
Instead, he just released a burst of CoC when he attacked and that's what Kaido felt.
Since Zoro wasn't using ACoC, just normal CoC, his AP didn't increase when he used Dead Man Game attack.
That proves Zoro's CoA is the strongest, or at least the strongest we've seen so far, since he scarred Kaido without ACoC and while severely weaken and injured. Zoro's poor condition at the time makes the feat even more impressive.
To everyone who tried to claim Zoro's attack was stronger because he was using ACoC, you have been proven wrong.
It doesn't stop there. I tried to tell everyone Zoro flying dragon blaze was incredibly strong and would have caused Kaido significant injury.
That attack was a combination of Zoro incredible physical strength and powerful Ryu. He was missing his physical strength when he scarred Kaido with Dead Man Game.
Some didn't want to hear it and claimed the results would have been no different than any of the attacks from the SN or Scabbards. Even though, Big Mom and Kaido we're terrified of that attack. There's no reason for them to be terrified if Kaido would have easily and quickly healed from that attack.
Of course, that was Zoro's haki. Not Oden's haki.
Everyone can see from the facts I provided Zoro's CoA haki is much stronger than we thought and his AP is truly on another level.
Zoro's built different.
PS: The fact King's unique power allows him handle and survive Zoro CoA haki attacks is insane and proves nobody's defeating quickly if they don't know his secret.