File ownership
Every file on a Mac records which user owns it. External drives normally ignore ownership, and Storage Studio doesn't keep it when moving to one.
File ownership is the record of which user account a file belongs to. Together with the file's permissions, it decides who can open or change it on a Mac shared by several people.
External drives are normally set to ignore ownership — you'll see Ignore ownership on this volume in the drive's Get Info window. On such a drive, every file appears to belong to whoever is using the Mac at the time, so a drive can move between Macs without permission problems.
Storage Studio doesn't keep a file's owner when it moves it to your external drive; the file's permissions and dates are kept. On a Mac with one user this makes no practical difference. On a shared Mac, keep it in mind before moving another person's files.
See also: File ownership on external drives · What a move keeps