When conflict detection is enabled, Cisco Defense Orchestrator (CDO) polls the device for the default interval to to determine if a change has been made to the device's configuration outside of CDO. If CDO detects that a change was made, it changes the configuration status for the device to Conflict Detected. Changes made to a device outside of CDO are called "out-of-band" changes.
In the case of an On-Prem Firewall Management Center that is managed by CDO, if there are changes that are staged and the device is in Not Synced state, CDO stops polling the device to check for changes. When there are changes made outside CDO which are pending to be synchronized with CDO and changes made in CDO which are pending to be deployed to the on-prem management center, CDO declares the on-prem management center to be in the Conflict Detected state.
Once this option is enabled, you can configure how often conflicts or OOB changes are detected per device. See Schedule Polling for Device Changes for more information.