This is Harriet (2022)

Allison, a pianist whose mother suffers from dementia, has been led to believe she's been selected by the parents of a young prodigy to play their son's concerto. She quickly learns, however, that her potential employers are deeply conflicted over what's best for the boy. The prodigy's father refuses to believe his wife's superstition about the source of a mysterious affliction that causes the boy to be beset by memories from someone else's life. Allison has an emotional breakthrough when she finally submits to her mother's belief that she is the mother's late sister, Harriet; an experiment that ends up ruining her prospects with the family.