For private unicorns I think the answer is no, I've seen plenty of good people join companies that are perceived to be likely to IPO soon. There's plenty of shady stuff that can still happen in late-stage startups, but I think the perception (which is probably somewhat but not completely accurate) is that at that point the equity is enough of a known quantity to be somewhat de-risked.

For earlier stage startups...yeah, I dunno. To be clear, I think the illiquidity and vesting period and all of that are basically fine, well-understood risks, and in principle startups can offer enough equity to compensate "true believers" for those risks. What gets me is the really shady unforeseeable stuff, like converting part of the acquisition price to retention bonuses avoid paying out ex-employees for their vested equity. Between that unquantifiable risk and the inherent risk and illiquidity of early startup equity, I'd personally discount the 409a valuation by something like a factor of 5 when evaluating a job offer from an early-stage startup.

I don't see a ton of people leaving FAANG or similar companies for early-stage startups, but obviously there are lots of engineers outside of FAANG companies, and I'm sure it helps that valuations are rich enough (or were until recently) to compete with non-tech companies on cash comp.