Missing folder from iCloud Drive

First of all, “the most recent operating system”, which you mention in your post, is macOS Golden Gate, which was released by Apple on September 14, 2026. But since you mention macOS Tahoe 26.6.2, there’s a contradiction. So I guess you did your macOS update some time ago.

Secondly, your Mac’s files are preserved on your Time Machine backups. (You do use Time Machine, right?) Here’s how to restore them from the Mac User Guide.

Recover files using Time Machine and Spotlight on Mac - Apple Support

vjwylie wrote:

No, I didn't think I needed to do a backup to a hard drive because I had iCloud.

Beware that iCloud Drive and iCloud Photos is NOT a backup but a sync service. I.e. any mistake you make is synced to other devices and the fix is to correct that mistake from the backup done with Time Machine or 3rd party apps like Carbon Copy Cloner or Super Duper.

iCloud is not a backup service. It's a synch service to keep files synched across devices. If a file is deleted on one device it's deleted everywhere. Contrast that with a backup where a copy of the file is made and stored somewhere where it's not used or updated and can't be easily deleted. You should be making backups of your important and irreplaceable stuff. If you rely on iCloud to do this then at some point you will lost some important and irreplaceable stuff for ever.

Start doing regular backups using Time Machine or an app like CCC. Once you've got in the swing of it then do a web search for "321 backups" and up your game.

vjwylie wrote:

No, I didn't think I needed to do a backup to a hard drive because I had iCloud.

But in your original post you said:

”… it removed a bunch of folders and files from my computer's desktop and uploaded them to iCloud …”

So you knew these ‘really important files” were not housed in iCloud for that period of time.

No backup, even from then? Oops …

Phone and iPad backups are an exception to the icloud-is-synch-not-backup point. But note that if you backup your phone to iCloud only items not synched with iCloud are backed up. So if, for example, you synch photos using iCloud then those photos are not backed up to iCloud when you backup your phone.

I've no idea what happened to your folder.