The state of California already mandated certain density improvements:
https://calmatters.org/housing/2025/10/newsom-signs-massive-...
There is another law that mandated local communities plan to manage housing to accommodate population growth or the local community loses it's ability to deny permits. Struggling to find that but it was well before 2025 I believe.
The more likely reasons is corruption and paying off rising CalPERS costs:
https://californiapolicycenter.org/repeat-pension-history/ https://www.ppic.org/publication/public-pensions-in-californ...