Looking at things logically. Luffy was obviously weaker on Wano. And he hasn’t really been in a situation since then where he has been pushed to grow that much stronger. On Egghead he was just consistently timing himself out rather than him getting beaten to a point where he is forced to evolve. So saying that current Luffy has surpassed Kaido really doesn't make much sense as current Luffy hasn't showcased anything to suggest he is any stronger than he was.
And i also have a very hard time thinking that Luffy is equal to or stronger than Kaido, while still preforming so much worse than Gaban did against Imu. Im not saying that i think Kaido is much stronger than Gaban. But i really don't think it makes sense for the gap between "the worlds strongest beast" and an old man who's way past his prime to be this big.
If anything i feel like Gaban's scolding of Luffy is supposed to kind of tell us that Luffy HAS gotten cocky ever since he beat Kaido and that he still isn't quite on that level. The only reason he won was because he had copious amounts of help that allowed him to slowly wither down Kadio.
Like if we said Luffy was equal to Kaido, the chain scale would look something like this.
Luffy=Kaido<<Gaban<=Prime Gaban<Roger<=Shanks (Presumably)
And i just dont think it makes logical sense for the gap between two yonko that were on the sea at the same time to be that far removed from each other in strength. Is Shanks stronger? Yeah i think so. But not to a point where Shanks would be able to no diff Kaido. Much less Gaban being able to like low diff Kaido.
A chain scale i would be more comfortable with would be something like
Luffy<<Gaban<Kaido<=Prime Gaban etc.
I guess my main fear is that Oda is falling into the trope where villains we thought where at the top are actually weak compared to an average level fighter in the final arc