I agree. The Founding States made the Commerce Clause (Constitution's Article I, Section 8, Clause 3) to give Congress the power to referee interstate trade disputes.
It's also not suprising that this Constitution-ignoring state legislation is coming from California. CA legislators are possibly unaware of the Commerce Clause as opposed to deliberately ignoring it.
State lawmakers in all states have also probably forgotten that their predecessors gave up the unique control of the federal Senate by state lawmakers as a consequence of ratifying the 17th Amendment.
How is CA regulating the egg market within its borders a violation of the interstate commerce clause?
CA is entirely within its rights to regulate the egg market within its borders.