Out of Mr. & Mrs. Smith
due to creative differences
https://www.hollywoodreporter.com/tv/tv-news/phoebe-waller-bridge-exits-mr-mrs-smith-amazon-1235008522/
Guessing she wanted to play her character as comedically awkward and clumsy (as she does), but the director doubted that she could maintain interest in that for a whole movie. I suspect she could have. Too bad that now we'll never know.