I think claiming political ideology as the reason people are leaving California is intellectually lazy because the situation is much more complex than that. I don't think people are moving from SF to Austin so they can carry guns in public places. As a former CA resident myself, I can speak to some of this.
When you look at CA, there are multiple areas/cultures you can look at (Northern, Southern, Central Valley, etc.)...it's almost like states within a state.
It's no secret that CA is expense to live just about anywhere. Because SO MANY people have moved to CA over the last several decades housing prices have always been high due to high demand. Couple that with high paying tech and venture capital in SF it's nearly impossible to save up for a house in a nice area unless your company IPOs. The cost of living is just higher, it has been like that for a long time but people are questioning whether the quality of life is worth the high cost of living.
Enter COVID-19. More and more jobs have the ability to work remote. A big reason people move to CA is for job opportunities and now when you're working from home indefinitely, it makes sharing a 4-bedroom apartment in the city much less desirable than moving to somewhere with land and a lower cost of living.
Yes, income taxes are higher in CA but there are also WAY MORE people in CA than any other state, so the state needs a lot of revenue. That said, property taxes are relatively low/capped if I'm not mistaken. In order for companies to retain labor they have needed to pay more so their employees can afford to live there. This is why you are seeing companies diversify their workforce to lower-cost areas, like Texas.
When I moved out of CA 3 years ago (for a job opportunity in NC), I remember reading articles about the "mass California Exodus". California is the most populous state so when people move out, it's considered an exodus by the other 49 states' standard. Do I think California will be a ghost town in a few years? Absolutely not, there are still great job opportunities, phenomenal weather, geography, etc. California's not going anywhere, that is until there's an earthquake that breaks it off so it can chill with Hawaii.
Just my two cents.