The way it worked (in my case at least) is that as part of my signing on with the fund, I consented to their ability to block my employment with anyone for 2 years post departure (technically, they could have blocked the FAANG job but there'd be no reason to - and similarly they could have approved a job in finance if it was sufficiently removed from what I was doing.)

There was no "money for the non-compete" involved, other than perhaps the premium baked into my compensation to begin with to make the deal attractive.