@fourtificial OneDrive is syncing the contents of your Documents folder, which may be the entire issue here. The red and blue icons in your screenshot indicate the status of the sync: many of the files and folders aren't syncing properly, probably because OneDrive is full. The easiest remedy is to either deactivate OneDrive entirely or at least disable the auto-syncing of Documents.
https://support.microsoft.com/en-us/office/choose-which-onedrive-folders-to-sync-to-your-computer-98b8b011-8b94-419b-aa95-a14ff2415e85
If you get an error, you may need to pause syncing and cancel the current sync first.
https://support.microsoft.com/en-us/topic/how-to-cancel-or-stop-sync-in-onedrive-4885c27e-3d89-4d69-be75-2646c71367d3
Before you do this, copy your "The Sims 4" folder in Documents > Electronic Arts and paste it in Downloads, which doesn't get synced by OneDrive. That way, you'll have a copy stored on your computer that you can work with even after OneDrive is out of the picture; disabling it or its auto-syncing often removes the local copy of the files and leaves only a single copy in OneDrive.
