Literally last chapter:
Literally at the start of the Egghead:
Take it back another arc if you want.
If Blackbeard could sense Luffy's Haki all the way back in ~230, then he wouldn't have been the only one.
Meaning Luffy's CoC should have been detected by others that saw him before and at Marineford - if that is how it worked.
If not Aokiji, you'd think legends like Garp and Whitebeard would know.
Take a seat, bruva. You lack the capacity.