Episode 5 of Ahsoka marked a dramatic turning point for the series. Reunited with her Jedi master, Anakin Skywalker, in the World Between Worlds, Ahsoka Tano had to learn one last lesson in order to return to the realm of the living. By the midway point of the episode, Ahsoka has come to realize what she is fighting for and has overcome the fear that has been holding her back. When her lesson is complete, Anakin allows her to return to the real world. The revived Ahsoka soon dons a white cloak, finally fulfilling a promise made by the series finale of Star Wars Rebels.
Source：https://www.cbr.com/ahsoka-the-white-significance/
