Can't remember the iCloud Security code, and do not have another Mac device

M1 Mac mini, Sonoma 14.6.1

iCloud Security Code, iCloud Keychain problem

I've looked through other posts from people with the same issues with the "iCloud security code" yet it never seems to be completely answered; this is not the same thing as an iCloud or Apple password, and it is not something that is solved with two-factor authentication.

The iCloud security code is a four digit PIN and it seems like it must have been set up in a previous iteration of iCloud, maybe years ago. I can't remember mine personally (though I have tried every four digit combo that I would ever use, and for some reason none of them have worked... which is strange), and when I click "Forgot Code?" I ONLY get a dialogue box with the message "If you can’t remember the iCloud Security code, you can approve this Mac using another device." That's it, no other options. The problem is -- I don't HAVE any other devices! My only other Apple computer was lost in a house fire months ago, and I don't think my modded 2006 Mac Pro would've been worth anything in this situation regardless.

The only reason I want this code is to get rid of the notification that I receive every single time I use my Mac telling me that my iCloud data isn't syncing. Please. Apple, PLEASE. Help me. I beg of you, PLEASE. What do I do?