When you bring in a Map Service in Pro, the feature layer(s) within are locked from any kind of properties management. You cannot view the attribute table, you cannot modify the symbology or labeling, and most frustrating, you cannot modify the popup properties. But, if you publish the web map with Map Services, you can go onto your Portal and edit all of those items in the very same map. This makes no sense. If you have permissions to edit the web map in your Portal, and as the creator of the web map, you should be able to perform any action in Pro that you can in the Portal. Besides, you shouldn't have to publish a web map just to be able to edit layer properties, sometimes you just need to bring in a service and create a simple web map that you can store locally.
I do realize that adding the individual feature layer within a Map Service provides this same kind of access, but that just proves my point that locking down a feature layer within a Map Service, when the parent Map Service is added, is pointless. Please bring your Map Service functionality more in line with web maps.
