LayerGroup contained styles are not fully expanded here https://github.com/geoserver/geoserver/blob/main/src/extension/geofence/src/main/java/org/geoserver/geofence/GeofenceAccessManager.java#L1213 causing exception later when they are retrieved according to the layer index.
main pr https://github.com/geoserver/geoserver/pull/5335
2.20.x https://github.com/geoserver/geoserver/pull/5350
2.19.x https://github.com/geoserver/geoserver/pull/5349
LayerGroup contained styles are not fully expanded here https://github.com/geoserver/geoserver/blob/main/src/extension/geofence/src/main/java/org/geoserver/geofence/GeofenceAccessManager.java#L1213 causing exception later when they are retrieved according to the layer index.