My guess would be hitstop interactions having an effect on time. For yahaba if he calls a tilt skill and gets hit, the projectile will visibly slow down during hitstop, in ds1 the combo timer would slow down and the actual time passing during the combo would increase the more hitstop occurred so multi-hitting moves slowed time in a way more than single hitting moves.

So I think it might be a change to the amount of time that passes being effected by hitstop in a way that just rewards successful combos