503 Service Unavailable

Yesterday in flow logs I saw next error:

Crash detected! Execution was interrupted by an unexpected exception: PrefectHTTPStatusError: Server error '503 Service Unavailable' for url 'https://api.prefect.cloud/api/accounts/...workspaces/.../flow_runs/.../set_state'
Response: {'exception_message': 'Service Unavailable'}
For more information check: https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/503

My flow is still running. My Prefect version is 2.14.20. Why did it occur and how can I handle it?