The key to this hand is whether North can apply the brakes in time to avoid playing in 7NT. Four of eleven Norths failed to do this when the hand was played.

South doesn't have anything like the 23 points normally needed for a 2♣ opener, but with only three losers can definitely open 2♣ .

This is where the first alarm bell might go off in North's head. North's 18 points plus 23 opposite for a 2♣  opener makes 41 which just isn't possible. Nonetheless North should make a positve 2♥ response which is forcing to Game. Now North-South can relax as the bidding will not stop below game. After 4♦ North is at the crossroads. There is nothing to lose (and everything to gain) from checking there is no missing Ace before bidding 7NT. When Blackwood shows South with only two Aces, North can settle for 6NT and pat themselves on the back when East leads the ♣ A.