When Windows users suddenly discover that their files have vanished from their desktops after interacting with OneDrive, the issue often stems from how Microsoft’s cloud service integrates with the operating system. The automatic, near-invisible shift to cloud-based storage has triggered strong reactions from users who find the feature unintuitive and, in some cases, destructive to their local files.
It switches to storing files on Onedrive without warning.
Then if you disable Onedrive, you lose access to your files (on Onedrive) and their memory space is reused.
It doesn’t actually delete local storage, as the path is just switched.