In Ventura, Monterey, Big Sur, and Catalina there is no default Data folder, but there is a Data Volume where all user folders, settings, and documents are stored. It is the only volume on the boot drive that you have read & write access to. Depending on Finder settings it may appear in the Finder sidebar, but not on the Desktop itself.
I have seen a window with Data Folder and, beneath it, Data Volume.... but don't recall where.
Just to get back to square one, what are the contents of your Data folder that used to be at the top level of your iMac but is now on your desktop?
If, as I believe you said at the get-go, they're simply YOUR data, joemike is off on a wild goose chase, i.e., your Data VOLUME has nothing to do with your issue, and your answer is what I've been saying: The folder, presumably because of some change in macOS, can no longer inhabit its original location, and the OS has relocated it to your desktop.
If I'm correct, you've got two options: You can either leave it on your desktop or create a new folder in /Users and populate it with your data.
And if not...
Never mind. 
