I understand from the other posts that there should be no subfolders to the collection.media folder. I haven’t moved any images. I simply copy and paste images and allow Anki manage itself. Indeed, as you know the library folder on Mac is hidden. I only discovered how to access it yesterday.
As far as I can tell all the images and sound files are all still there. There is one subfolder (not put there by me) in collection.media folder the called "file/“. That has a collection of empty folders. It runs as below:
You appear to have synced a bunch of media deletions on the 21st. If you're unable to locate the missing media files in your trashcan, please let me know and I can restore the m from an AnkiWeb backup.
Anki won't have created that folder itself - if it's empty, I'd suggest removing it.