This is a consequence of foreign cash buyers, many of them coming from China. We have had a decade long influx of foreign buyers in SoCal who have driven prices above what California natives can afford even on two salaries. In my area 40 yr old tract houses are getting $450/sq ft.
This prices out new buyers, at least the ones born here. And these high prices get passed along to renters. Some are grandfathered in with landlords who aren’t marking rents to market. But if a place sells those renters are out of luck and they will never find places renting for close to what they had been paying. Very hard on the elderly who have been renting for decades.
Another huge problem is all the housing being occupied by illegal aliens. The ones who don’t plan to stay here are willing to live 20 to a house and that allows them to pay very high rents while turning the neighborhoods into dumps.
LA has been an expensive area for real estate for much more than a decade, so blaming the Chinese isn’t going to explain it. Going back to post WWII, look at real estate prices in LA compared to the national average. It’s been a problem for at least 60 years. Also, look at what happened after rent controls started in LA in 1978. Those controls just made things worse...as they always do.