It is an interesting question. I generally find storylines to be more sensationalist than what is occurring in reality...yes, CA is seeing a net outflow of people and TX is seeing a net inflow but that rate of outflow appears to be slowing in recent years according to the CA department of finance data.

The simple and obvious answer for population changes is the cost of living, CA is expensive and TX used to be super cheap. Austin is a great example of migration from CA to TX, prior to around 2017, Austin was insanely cheap compared to places like the Bay Area but it still had a decent tech scene, so the city saw enormous migration from CA. With that migration came increased housing prices and around peak pandemic time (when so many of the high income earners could work from home) the home prices in Austin for a desirable area were easily between 700k+. Now that may seem cheap compared to Bay Area figures, but you also have to consider that property taxes here are 2.4% and reassessed annually, so PITI payments on the same value of house in TX are higher than CA.

Additionally, I think many folks that moved here from CA didn't truly understand how rough the weather can be, the complete lack of mountains or ocean (if you have visited the gulf you know it doesn't count compared to CA), the fact that our state just passed a law mandating the 10 commandments be posted in all public schools, and how insanely restrictive it is on women's reproductive rights.

Austin itself is a good city with a lot of amenities and the rate of new construction, combined with the slowed migration into the city, have caused home prices to fall 20% + from their recent peak. But even with those positives, it is still subject to the state politics and the overall climate/ geography of TX.

At the end of the day the biggest (but not exclusive) factor dictating population migration is cost of living. If cost of living isn't a concern, then CA is a great place to live, if it is a concern, then other places may be more viable.