From experience unless the person mention their next "adventure"(within like a couple of months) or gig it usually means a manager or c-suite person got axed and was given the option to gracefully exit.
By the barrage of exits following Mira's resignation, it does look like Sam fired her, the team got the wind of this and are now quitting in droves. This is the thing about lying and being polite. You can't hide the truth for long.
Mira's latest one liner tweet 'OpenAI is nothing without it's people" speaks volumes.
