Any progress on this from the developers?
From myself I will add: it is important to create a delete delay (since I can move the attachment to another place via cut). Delay for example from 5 minutes to several days. I understand that technically this is not the most trivial task as optimization is required. But I think deleting attachments may be part of indexing - in any case not all files were edited after the last indexing, etc.
External solutions are not satisfactory, e.g. a post written 18 days ago on Reddit:
Update 2025 - just tried using this and it deleted images attached to some of my notes. I uninstalled this plugin.
/r/ObsidianMD/comments/10nntrg/cleaning_unused_attachments/