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.
See two examples below. Oddly, I’ve found that the images are retained on the Mac but don’t show up on the phone. I’ve tried, of course, to synch to solve but the cards on the two cards on the phone remain the same, without image
Lucia e Marco si sono sposati __ la famiglia fosse contraria. / Lucia e Marco si sono sposati nonostante la famiglia fosse contraria.
That file is in AnkiWeb, so it looks like it hasn't been downloaded by AnkiMobile yet. Please log out in the sync preferences of AnkiMobile then sync again, which will force a full scan for any missing media.