A Microsoft file hosting and synchronization service.
Dear Mohamad Farid Bin Johari,
Good day!! Thanks for posting your concern in this Microsoft community.
As per the description shared, I understand your concern and to my knowledge, I would like to convey that the OneDrive size showing on the synced folder is not the actual size of the OneDrive for Business because the OneDrive synced folder doesn’t show the size of the version history of the files.
So, to check the accurate storage of the OneDrive for Business, we need to go to the Storage Metrics in the browser:
Open the OneDrive for Business for the browser> Settings> OneDrive settings> More Settings> Storage Metrics> Documents> Check the storage of the each file and delete the versions of files which are not required.
Post deletion, please delete them completely from the first and second stage of recycle bin for OneDrive for Business.
Appreciate your patience and understanding. Have a great day!!
Best Regards,
Sophia