CR2 files of my dream photo location seem to be corrupted. Is there any hope?

[Svdb]

Dear Exiftool users,

I've been traveling to Norway for photography and made a backup of my SD and CF cards on a daily base to 2 external HD's.
I created a new folder on the external HD's for every day, containing both my CR2 files (most important to me) and AVI files from my Canon 5dmk4.
I'm back home now and realise that for 2 of my image folders, 20220217 and 20220218 there seems to be no image preview available... this is the first OMG!

Non of the default applications (OSX Preview, PS) seem to be able to open the images in these 2 folders. I'm talking about 1800 images from time-lapse creations etc. The CR2 files are all about 40mb in filesize. At least, thats what OSX Finder tells me.

I've tried all kind of solutions, from image recovery tools - unfortunately I didn't realise there was something wrong with these files during my trip, so I kept on formatting and re-using the same SD and CF cards the days after, and therefore recovery programs don't seem to be able to go back multiple days, probably its been overwritten too much - to repair solutions, renaming files, checking exif editors - which I dont understand exactly how to use them, using the extract_preview script provided in this forum, but nothing seems to be able to give me a preview from these photos.

What worries me a lot is even though the filesize seems to be proper (about 40mb each), when I zip a file, the archive is only about 30kb. While this is not the case for all other intact image(folders).

Is there anyone, who can please give me some advise on what else I can do or do I have to accept that those images are corrupted and impossible to restore?
I have added 1 of the unreadable CR2 files to a Dropbox folder: https://www.dropbox.com/sh/m5pr2ft9ielklka/AAAtNTRxVTEYQm1iedab6LLla?dl=0

Just to be clear, I think I have made a mistake by copying the images from my first backup HD to my second backup HD instead of copying directly from my SD/CF cards to both of the Backup HD's. So, yes... on both external HD's the same thing is going on. This is the second OMG!

Please note, that when I'm copying these files to another device it takes a while, so I'm guessing that the 40mb filesize is correct, but I have no idea which data it contains.

Thank you in advance.
Kind regards,
Svdb

[StarGeek]

What worries me a lot is even though the filesize seems to be proper (about 40mb each), when I zip a file, the archive is only about 30kb. While this is not the case for all other intact image(folders).

The files that zip up this small are irreversibly lost.  If there was even a preview image that could be extracted, it would be at least a couple hundred kb, if not at least a meg.

You can try Phil's brute force extract preview script (you need Perl installed), but don't expect miracles.