https://docs.paloaltonetworks.com/pan-os/9-1/pan-os-admin/quality-of-service/qos-concepts/qos-classes

When an administrator needs to evaluate recent policy changes that were committed and pushed to a firewall device group in Panorama, the most direct approach is to use the "Preview Changes" feature.
A . Click Preview Changes under Push Scope:
The "Preview Changes" option is available under the "Push Scope" in Panorama. This feature allows administrators to see a detailed comparison of the changes that are about to be pushed to the managed firewalls or that have been recently pushed. It highlights the differences between the current configuration and the previous one, making it easier to identify exactly what changes were made, including modifications to policies, objects, and other settings.
This is particularly useful for auditing and verifying that the intended changes match the actual changes being deployed, enhancing transparency and reducing the risk of unintended configuration modifications.
This approach provides a clear and concise way to review configuration changes before and after they are applied, ensuring that policy modifications are intentional and accurately reflect the administrator's objectives.

https://docs.paloaltonetworks.com/panorama/9-1/panorama-admin/manage-firewalls/manage-device-groups/manage-unused-shared-objects
https://knowledgebase.paloaltonetworks.com/KCSArticleDetail?id=kA10g000000Cm1CCAS