Doesn't California have a bunch of debt?
Depending on who you ask and what you count (e.g., pension liabilities), anywhere between $200 billion and $1 trillion. All these numbers always seem to be practically random. You can visit 100 different websites and get 100 different sets of numbers.
The last thing Jerry Brown said before he left (and I have to give him credit for it) is that the surplus should be saved for emergencies and not used on new projects and harebrained schemes. He was very clear that state tax revenue will be going down drastically in the next few years. Newsom apparently let it go in one ear and out the other, and as Mike said, will just use "other people's money". Though those "other people" are beginning to say "no" in a number of different ways.
Plus all it will take is for one of the "tech giants" to say they've had enough and move a majority of their infrastructure to another state. They're all pretty commie-sympathetic, but at some point they'll have to fish or cut bait when the progressive state tax burden gets to be too much for them.
https://www.sandiegouniontribune.com/opinion/sd-california-budget-surplus-pensions-20181115-story.html