It appears to me that Qualified Charitable Distributions are not subject to California state income tax to the same extent that they are not subject to federal income tax.
In 2015, in a Summary of Federal tax law changes, California published, "California’s Personal Income Tax Law generally conforms by reference to the federal IRA rules under IRC section 408 as of the “specified date” of January 1, 2015.236
236 R&TC section 17501(a) conforms to Subchapter D of Chapter 1 of Subtitle A of the IRC (consisting of IRC sections 401 to 436), relating to deferred compensation, except as otherwise provided.
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In other words, the Personal Income Tax Law automatically conforms to federal changes made to IRC section 408. As a result, this provision that makes the exclusion for qualified charitable distributions permanent automatically applies under California law (i.e., the exclusion from gross income for qualified charitable distributions from an IRA is the same for federal and state purposes). " See page 115 at https://www.ftb.ca.gov/about-ftb/data-reports-plans/2015-Summary-of-Federal-Income-Tax-Changes.pdf
CA Rev & Tax Code § 17507 (2017), paragraph b, does not describe any modification to IRC 408 that would cause CA treatment of a QCD to be different from the federal treatment. See https://law.onecle.com/california/taxation/17507.html
The current IRC code referring to these distributions can be found at IRC Section 408(d) - (https://www.law.cornell.edu/uscode/text/26/408).
