tilda swinton had to reshoot avengers: endgame scenes because of these plot changes /

One of the great surprises of Avengers: Endgame was the number of unexpected cameos in the film,including one from the great Tilda Swinton as the Ancient One, the one-time Sorcerer Supreme who tutored Dr. Stephen odd in the mystic arts before leaving this mortal coil behind in 2016's Doctor odd.

Source: blastr.com