Slur collision avoidance
By default, Dorico for iPad automatically adjusts the shape and position of slurs to avoid collisions with items under their arc.
This means that if a notehead under a slur is either higher than the others under a slur curving upwards, or lower than the others under a slur curving downwards, the curvature of the slur is adjusted to avoid the collision and keep the notehead under the slur. You can manually disable collision avoidance for individual slurs.