Explanation
https://docs.paloaltonetworks.com/pan-os/10-0/pan-os-admin/decryption/decryption-concepts/decryption-mirrori
"Keep in mind that the decryption, storage, inspection, and/or use of SSL traffic is governed in certain countries and user consent might be required in order to use the decryption mirror feature. Additionally, use of this feature could enable malicious users with administrative access to the firewall to harvest usernames, passwords, social security numbers, credit card numbers, or other sensitive information submitted using an encrypted channel. Palo Alto Networks recommends that you consult with your corporate counsel before activating and using this feature in a production environment."