I think people have erased from their memories that Kaido was also seeing the visage of Oden while he was fighting Gear 4 lol. Kizaru really did a number on them.
Kaido's intro and its consequences....lol. I feel like people are stuck on him as this One Piece equivalent of Worldbreaker Hulk or something. He's strong but not
that strong.
Also idk what's with the fandom and underrating Marines. I thought Garp at least was free of downplay but from what I hear even he got downplayed by some back in the day.
As for Kizaru, his thing is that he's not Fleet Admiral or narratively relevant so he gets downplayed a lot based on those metrics. People can't see him as being stronger than he's "supposed to be".
I have him as the #2 Admiral based on patterns but I know I'm in the minority.