I don't that's really generally true. If it seems like the company is a "sinking ship", then yes, people who can see the writing on the wall and have food opportunities elsewhere will often leave quickly.
But in this case, nobody is worried about Stripe's long term trajectory or viability. I doubt the best and most employable people are leaving Stripe.
Imagine you had a recruiter call you for this next gig at great company which has +20% salary bump. Once you hear something bad is coming in your current company and no idea if you will be caught in it or not, its much easier step to just go and accept the next offer that you would otherwise pass.
But in this case, nobody is worried about Stripe's long term trajectory or viability. I doubt the best and most employable people are leaving Stripe.