You are attempting to share a clustered feature layer as a map image layer or feature layer to a version of ArcGIS Server that does not support clustering. Publishing a clustered feature layer or including it with the web map requires ArcGIS Server 10.9.1 or later.
Do one of the following:
- If sharing as a web map image layer, remove the clustered feature layer if it is not needed.
- If sharing as a web feature layer, turn off the visibility of clusters.
- Upgrade the server, or publish the layer to a server with version 10.9.1 or later.