I'm giving MarineHQ a few hours to revel in it before I dump on Kuzan for being a weak version of Garp
Admiral fans will just say Old Garp can push Prime Garp to high/extreme diff despite Garp himself admitting he’s a weakling compared to his former self.
They pulled the same shit in MF. Oldbeard literally couldn’t use his CoO anymore (which used to be so good that he could sense in his sleep Ace attacking him) and couldn’t use his ACoC or even just basic CoC anymore (we can also surmise that his CoA was severely nerfed too). And there was also Croc and even Marco admitting that WB is a shell of his former self. Despite that, Admiral clowns still claimed Oldbeard is a high diff for Primebeard.
The reality is that Old Garp is a mid diff for Prime Garp, and as per Kuzan’s own admission, Old Garp pushed him to his limits despite Shiryu giving Garp a “grievous wound” (Kuzan’s own words) and the other BBPs being shown interfering in the fight