The Add Shortcut to OneDrive feature has been retired from the tenant as of January 2022. This feature previously linked a SharePoint folder within the user's My Files section of their OneDrive. Existing shortcuts made this way will continue to work, however no new shortcuts can be created.
This article provides tips for those who have existing shortcuts.
1. Shortcuts respect the settings of the originating library, so if Sync is disabled on the SharePoint library, users cannot Sync the shortcut. They will in fact get a OneDrive error message if the user has OneDrive Sync enabled. Examples include: "A shortcut no longer works".
2. If the user already has a Shortcut in their OneDrive and is Sync'ing their OneDrive, they cannot Sync the library/folder directly from the SharePoint site. They will receive an error message saying the folder is already sync'd. "Sorry, we can't sync this folder. You're already syncing a shortcut to a folder from this shared library."
In this case they will need to either continue as-is with the shortcut falling under their OneDrive Sync, or else remove the shortcut from OneDrive and then re-Sync directly from the SharePoint library.
In OneDrive, in the My files view, select the shortcut folder you want to remove.
Select Remove shortcut from the menu.