While performing some site optimization work for a client, I encountered a plug-in that replaces the selected image feature of WP with a separate meta-box that allows you to specify an image URL rather than import the image into your own media library.
Recent updates to this plugin broke my client's site, where posts containing external featured images did not display them. And examining the code of the plugin itself (mediocre documentation, direct SQL queries on the database) lets me believe that he does not really know what he's doing.
For my client, I have created a custom plug-in to browse publications with the meta keys of this plug-in, import the image into the media library and attach it to the message. Finally, it removes the meta key from the other plugin.
Now, I have no qualms about running the patch on my client's site, but I'm also considering inserting the plugin into the WordPress plugins directory. And maybe even a "premium" version with monetization.
I've gone through the WP plugins' code of conduct, but I have not seen anything listed regarding editing the meta-entries of another plugin. Is there something that does not respect ethics?