Behavior Regulation: Not Allowing Texting Coworkers During Non-Work Hours. Manager Cc'd in All Texts

My question involves labor and employment law for the state of: California

Our manager doesn't allow coworkers to call or text each other outside of business hours. Texts that are sent during business hours, the manager requires employees to add that manager so they view all employee conversations. All this communication is done on employee personal phones. We were threatened with punishment for not following those rules.

I'd like to know what my rights are, and if I have any protection from these rules.

Behavior Regulation: Not Allowing Texting Coworkers During Non-Work Hours. Manager Cc'd in All Texts