The film, which is being directed by Ms Marvel's Sharmeen Obaid-Chinoy, was first announced last year, and is set 15 years after the events of The Rise of Skywalker.
However, it is now being reported that Knight has exited as screenwriter, with Lucasfilm currently talking to potential replacements (via Variety).
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The Peaky Blinders boss originally replaced writers Damon Lindelof and Justin Britt-Gibson, who themselves dropped out of the project early last year.
The untitled movie is set to follow Ridley's character Rey as she trains a new generation of Jedi, with Lucasfilm boss Kathleen Kennedy previously admitting that they "knew coming off of The Rise of Skywalker that we needed to take that further".
"We just didn't know how far out; we didn't know exactly what the story might be - but now we have a much better idea," she added to Yahoo UK.
Speaking last November, Ridley revealed that the storyline for the project was not what she expected.
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"I'm very excited," she teased to Collider. "The story is really cool. I'm waiting to read a script because, obviously, I don't have any other updates. It's not what I expected, but I'm very excited.
"So far, I know the story of one film, and I think people will be very excited."
The Rey film is one of several Star Wars big screen projects in the pipeline, including The Mandalorian & Grogu, and movies from Dave Filoni and James Mangold.
Meanwhile, Knight is currently busy working on the upcoming Peaky Blinders Netflix movie, which will see the return of Cillian Murphy as Tommy Shelby.
Star Wars: The Rise of Skywalker and the entire Skywalker Saga are streaming on Disney+ and also available to buy on DVD, Blu-ray and 4K.