https://scocablog.com/exit-taxes-in-california-not-so-fast/
Especially egregious was a 10-year look back so even if you left years before the taxes would take effect, they'd still fleece you.
The way California's finances are going, and the way the state is degenerating, it's only a matter of time until they get serious and pass some form of this. It probably won't pass legal muster, but they'll do it anyway and spend years fighting it in courts.
https://www.upstartwealth.com/blog/will-you-owe-ca-tax-after...
Based on this, it seems like "exit tax" is a bit of a misnomer -- the proposal was just to tax people even after they've left California, but they would have paid the tax even if they hadn't left.