Synology NAS data sync to SharePoint (data size larger than source)

Hi Everyone, I have a question the data size after sync from NAS Synology to SharePoint.

I have sync data from NAS Synology to SharePoint using Cloud Sync.

Why the sync result data from NAS Synology to SharePoint is bigger in size than the existing data in NAS Synology?

Maybe someone knows, please let me know. Thank you