Prop 47 at the state level, plus local-level decisions to not go after misdemeanors, plus political influencers telling the public not to report crime because ACAB or whatever.
I've certainly read theories that it's a malicious strategy of the police union to make the city council look bad, and the SPOG president has made some pretty shocking political statements, so it honestly wouldn't be that surprising.
I'm guessing it's a mix of both, but I can't really prove anything.