What to do with pages that still have the 'page_image' property with a free (Commons) image as its value?
Topic on Extension talk:PageImages
What problem are you trying to solve?
No real problem, just improving the quality and consistency of the database, and therefore make it is easier to use.
E.g. nlwiki-20190801-page_props has one page with both page_image and page_image_free and four pages with just page_image (all pointing to Commons images). Most of these have page_links_updated > 2019-04, so I would have expected these old properties to have been cleaned up.