Kizaru was dominating Rayleigh in a SWORDSFIGHT. He said himself that his subordinates are strong enough to take care of the Straw Hats and thus he only needed to put Rayleigh in check. While Rayleigh stated himself (while huffing and puffing) that he would help the Straw Hats if he could. So actually it was Rayleigh going all out serious while Kizaru just easily had him in check without even making use of his DF properly - he just easily matched the Dark King in his own element: swordsmanship.
To be fair, Rayleigh probably also kept in check physically to be in a decent physical condition even if he was whoremongerin and all that, only he never had to make use of a sword for over 20 something odd years, his physical strength would've probably been ok, so would his haki.
But Rayleigh would never be able to escape if Kizaru could make use of his light abilities, I mean come on lol
So I think its fair to say conqueror's nullify df powers. Again, this explains how Rayleigh escaped, Roger never commenting on admirals, Kaido not seeing admirals (lol) in his recall, Akainu being wary of Wano, the extreme shock in every marines faces when Luffy displayed it I mean Akainu looked pissed ass fuck lol, I mean the list probably goes on wiht way more hints I cant think of at the top of my head, hinting at there being a quality to conqueror users being able to nullify df powers. And I'm saying conquerr users that are adept with their powers like Rayleigh and yonkos.
Admirals all proved to be masered Haki user. They showed Advanced Feats for both CoO and CoA. We dont even know if they are CoC users or not - cant make any assumtions on that yet, whether if they have or have not. But that wont make any difference whatsoever anyways.