https://www.cnet.com/news/nasa-replaces-boeing-starliner-astronaut-before-first-crewed-launch/

"Boe is unable to fly due to medical reasons," NASA said in a statement Tuesday, but he will stay on the mission as assistant to the chief for commercial crew at NASA's Johnson Space Center -- the role Fincke previously held.

Fincke is a seasoned replacement, having completed three space trips since joining the astronaut corps in 1996. He has spent 382 days in space and performed nine spacewalks.