Official comment
Just so you're aware, rekordbox does not create the "folder" element; those are songs you already had on the USB drive. So if you had a folder called "My New Hits" and subfolders for each year you could browse those like:
Folder > My New Hits > 2019
Folder > My New Hits > 2020
Folder > My New Hits > 2021
Those are not analysed / exported by rekordbox - they are just files on the drive.