Legal Question in Employment Law in California

Your employer is correct to have you punch-out to show, on the record, to show that you did get a lunch break.

However, if you are made to punch even when you don't get a full 30 minute uninterrupted lunch break, then your employer is breaking the law.

I advise employers to require punch out/in for all breaks and lunches you actually take. It is not only legal, but necessary, to avoid false claims of 'denial' of breaks, or in your stated situation, false claims of 'change of time cards' and unpaid time.