Only time employees leaving is a bad sign had been when the company had been in zombie mode too long(few years) and haven’t delivered anything yet or still in alpha/beta stage with crappy deliveries no one is using or has no significant uptake.
Also, if there are financial difficulties, then a lot of people leave in droves and some actually come back after finances get better.
Would it really have been so hard to find out Sam Altman just got fired without notice?