It appears that you cannot deduct this expense. With regard to tenants, this appears to be simply a rent increase that would otherwise not be permitted under local rent control.
It appears that various bills have been introduced in the California legislature to provide some kind of state tax credit for these expenses, but none has been signed into law as far as I can tell. Looking at the current legislation in committee, https://leginfo.legislature.ca.gov/faces/billTextClient.xhtml?bill_id=201920200AB234, it also seems that the credit would be provided to only building owners, in part for amounts not passed on to tenants that otherwise could be passed on, not a credit to tenants.
