He dropped Vingegaard with a Purito style attack, with 1km to go, on the steepest part of the climb.For this reason, I can't understand why people expected Pogacar to win a lot more time. Maybe on San Luca but that's it. He still attacked on Galibier during a huge headwind and was able to break Vingegaard in a very shallow climb.
Just calling it dropping him on a shallow climb is IMO a bit misleading, it was 1km at over 9%.