Four things build the tall proud dome, usually missing one or two at a time.
Full gluten first - pav dough needs a proper windowpane so it can trap gas and climb instead of leaking and spreading. Under-kneaded dough makes short wide buns.
Equal, snug portions - weighed balls (50-60g), crowded so they just touch as they proof. Crowded balls have nowhere to go but UP, and they hold each other's walls. Lonely spaced balls slump sideways.
Full proof - bake at the jiggle-and-slow-dent stage, properly doubled. Even ten minutes early costs visible height... underproofed pav bakes dense and squat because the oven spring has no foundation.
And a hot, humid bake - fully preheated oven, and covering the baked buns with a cloth right after the butter polish keeps the tops soft and rounded as they cool instead of firming flat.
Weigh, crowd, wait for the jiggle. The domes will come.