No, it really isn't. Again, just mandated Prop 98 state spending on K-12 is $127.1B for next year, with this year's enrollment at just about 5.8 million students. That works out to $21k per pupil not including all discretionary state spending, federal spending, and other local funding (like the fundraising you're talking about).
> districts that are above some threshold don't get enough funding to operate
Since 2013, under the LCFF, districts with a very high amount of property tax revenue only get "basic aid" from the state, but this is only a small fraction of school districts. Anyway the funding disparity is the entire point of the LCFF: The idea is to give rich districts less and poor districts more.
It's frustratingly difficult to get my fellow Californians to understand that our schools are, if anything, over-funded, and that throwing ever more money into the black hole is unlikely to improve our abysmal outcomes.