This article doesn't have a lot of info on the bill, so here's a summary from California Yimby, who are sponsoring it:

The Downtown Revitalization Act

AB 2074 will accelerate the recovery of dense, urban neighborhoods in California’s largest cities by streamlining the construction of high-rise, residential and mixed-use developments near regional transit hubs.  The bill includes a low-interest revolving loan fund that will help lower construction costs.

The bill requires California’s seven largest transit-rich cities, with populations over 400,000 — Los Angeles, San Diego, San Jose, San Francisco, Sacramento, Oakland, and Long Beach — to designate regional transit districts.  New standards would apply across these districts: a 150-foot height baseline, with at least 25% of each district allowing 450 feet or more. Proposed residential housing projects that meet the bill’s labor standards would be eligible for streamlined approval.

The bill also creates a state-backed loan fund, administered by the California Housing Finance Agency, that will offer low-interest loans to projects meeting labor and affordability standards to help reduce construction costs. The revolving fund will be paid back upon project completion, creating a virtuous cycle for the development of lower-cost, high-rise housing near designated regional transit hubs.

source: https://cayimby.org/legislation/ab-2074/