In SDL Docs CMS, users can delete a publication, even after it has been published to Dynamic Delivery and has a "Draft" status. This results in entries in the broker database that cannot be removed because they are no longer associated with any item in the CM database. Over time the orphan items keep increasing in the broker database and could be part of the content returned from the PCA service. This could result in unexpected content to different clients consuming content from PCA.
I suggest forcing the condition "allow delete only if not published" when deleting an item from CMS.