Apple Numbers document disappeared from iCloud

Apple Support says I should ask a new question as Numbers Files Disappeared from iCloud Dri… - Apple Community has not been updated in some time.

On the 23rd of December, I updated a task log in Numbers I've been keeping for three years in iCloud on my Windows PC at work (Chrome browser). Fast forward to today, the 26th of December, and the file is completely gone. It's not in "recently deleted" and I can't find it in any document manager. I did make a backup to my PC as an Excel document, but it's only backed up to last week, meaning everything I did on the 23rd is completely gone. This is very upsetting that a file can spontaneously vanish from a file service I've otherwise had no problems with.