Yes, but:
(1) OpenAI salaries are not low like early stage startup salaries. Essentially these are highly paid jobs (high salary and high equity) that require an NDA.
(2) Apple has also clawed back equity from employees who violate NDA. So this isn't all that unusual.
https://www.sec.gov/Archives/edgar/data/320193/0001193125220...
It has happened in several cases involving leakers, most recently the Andrew Aude case.