I had two 30 min interviews with four different people. It was straight forward, but they would ask a lot of follow up questions and really stress test your pitches.

The fellowship directors screen the applications and pass on promising candidates to desk editors. A month or so after the application deadline, I was emailed directly by an editor on my eventual desk. I interviewed with them and one other editor (at the same time) over a video call. There was no writing test or other exercise. I personally didn't have a second interview, although I've heard other desks conduct two or more rounds.