When you depart from OpenAI, as Jan Leike, Ilya, and several others have recently, you have to sign a restrictive agreement including nondisclosure and non-disparagement clauses that are set for life.

"One former employee, Daniel Kokotajlo, who posted that he quit OpenAI “due to losing confidence that it would behave responsibly around the time of AGI,” has confirmed publicly that he had to surrender what would have likely turned out to be a huge sum of money in order to quit without signing the document."

This seems totally fine and normal.

https://www.vox.com/future-perfect/2024/5/17/24158478/openai-departures-sam-altman-employees-chatgpt-release