I lose Sharepoint sync

We have all company files shared in SharePoint and synced with OneDrive.

Lately it has happened to us that some users, not all, suddenly have the synchronization fail, all at the same time, with a Onedrive notification appearing on the desktop saying "Folder was deleted. Folder will stop synchronizing. A copy of these files will be left on the PC".

If the user doesn't realize it, they are still working on the files, but they are not syncing to SharePoint. Why could this be happening?