When a full sync occurs in a Federated setup, the policy object can be removed, but the management object remains, later when the object is recreated, it fails as the object still exists in manager.
This issue can occur on other objects also, it is not limited to Tier 0 gateways, such as Tier 1 gateways, segments, etc.
The same API above can be used to check realization status, just replace the intent path with the object being investigated:
https://<GM-IP-Address>/global-manager/api/v1/global-infra/realized-state/status?intent_path=<intent-path>