Note To determine which OneDrive sync client you're using, see the following Microsoft website:
When you synchronize a Microsoft SharePoint Online or OneDrive for Business library to your computer by using the OneDrive for Business sync application, a file that was synchronized is unexpectedly moved from the SharePoint Online or OneDrive for Business library to the SharePoint Online or OneDrive for Business recycle bin.
You can confirm that the file wasn't intentionally or accidentally deleted by the user who is listed in the Deleted By field. This is important when multiple users are synchronizing a single library. For example, in some cases, a user may try to copy a file that may have been accidentally moved to another directory. This removes the file from the synchronized library.
If the file wasn't intentionally or accidentally deleted, you should have the user who's listed in the Deleted By field review his or her computer to determine whether a local process moved or deleted the item. For example, local virus-protection software may be configured to quarantine files.