This article mentions the allegations, but you can also read them directly here:

https://cims.nyu.edu/~tristanb/statement.pdf

"Buckmaster has questioned whether OpenAI's systems had been exposed to his private mathematical drafts, which he had been feeding into the company's tools during the year."

Duh, of course the research and personal information theft tools steal.

"When Buckmaster indicated that he intended to speak publicly about the situation, he says he was told, “Why would you ruin your career?”"

That is mild. Remember what happened to Suchir Balaji.

Congrats to OpenAI!