The article erroneously conflates assault rifles with semiautomatic rifles of a certain appearance (so-called assault weapons). It's 2021 and media still don't know shit from Shinola.
A quick search revealed no semiautomatic rifle manufacturers in CA, but I could be mistaken. If passed, the proposed law would apply (briefly) to firearm retailers before being struck down along interstate commerce/restraint of trade violations.
The issue of "ghost guns," though, is a separate matter.