As the concept has been about people leaving CA for other states, per this article in the Sac Bee ( https://www.sacbee.com/news/databases/article236910698.html )-Yeah people are leaving, but they are almost immediately replaced. That's why the population has mostly still increased over the last 10 years (or if you want, as a compromise, we can agree has stayed flat compared to other states).
"From 2015 to 2017, California saw a net loss of between 129,000 and 143,000 residents to domestic migration each year, according to census estimates. ... California has lost more people to other states than it has gained for much of the last two decades, census figures show."
Also the previous article I posted several days ago stating CA is expected to lose a congressional seat for the first time... AZ and TX expect to gain (3 for TX).