The only thing the latest chapters proves is that there are higher levels to CoA. No, I'm not talking about a level beyond internal destruction haki. I'm talking about higher levels to barrier haki. IE: Let's say there are 10 level to CoA barrier haki. Zoro could be a 6 and might Greenbull is a 8. While Ryuma and Mihawk are both 10.
It's crazy that the same Zoro who could cut and scar Kaido had problems damaging King. Zoro scarred Kaido's body without ACoC yet still needed ACoC to damage King. ACoC Zoro would have cut Kaido's body in half.
It's a good thing Kaido didn't face Greenbull. He would have pierced Kaido's body like it was nothing. Cut and ripped him into pieces. Made Kaido his bitch.
To think, G5 Luffy with his ACoC and Internal destruction ACoA couldn't even break a single scale.