I suggest adding functionality to the "Sync Layers" process to maintain Metadata for Bulk-Published layers from a relational database:
This is probably analogous to using an "Overwrite" of the existing bulk-published feature services which maintains an ItemID and updates content and metadata
ArcGIS Enterprise 10.7.1 introduced the ability to publish layers in bulk from a user maintained geodatabase (Publish layers in bulk from a user-managed data store—Portal for ArcGIS | ArcGIS Enterprise) - a feature that will save us many hours of manually publishing individually selected layers as ArcGIS Enterprise layers. One of the strengths of the process is, that it brings along all the metadata that you have in the "Description" pane in ArcGIS Pro.
To update what's getting published, there's a "Sync Layers" button that does just that: new layers will be published if the registered DB connection can "see" new layers and, conversely, those that it can no longer "see" in the DB will be retired removed) as layers from ArcGIS Enterprise.
I love the functionality but in my view it has a flaw:
Metadata from the Database are published at the time when a layer becomes first available and if the metadata in the DB is updated later, that will not get reflected in the published layer. We will occasionally update both content as well as Metadata in our SDE database and will want that to be reflected in the publithished layers.
Currently only content updates will flow through to the portal automatically, when SDE content is updated, not Metadata.
Currently what we need to do when this happens, is to delete the layer from the layers published through ArcGIS Enterprise and re-run the "Sync Layers" process. This will publish a NEW layer for the dataset in SDE - along with its Metadata.
Obviously then, the ITEMID will be a new one, too - and therefore all web maps and applications that had been built using the first instance of the layer will no longer work - a pretty big issue for us as, by design, we want people to use these layers for their own maps and applications. For a single layer we could do some wizardry with the ArcGIS API for Python to update what ItemID is referenced but it would be far simpler if Metadata were updated when the database content is updated.