The Switch eShop automatically downloads the latest version (currently beyond 4.0.2a). While you cannot roll back to 4.0.2a easily, you get all content, no bans, and full online functionality.
The NSP Update 4.0.2a brings several new features to Asphalt 9 Legends, including: Asphalt 9 Legends -NSP--Update 4.0.2a-.rar
This is likely a update file (NSP = Nintendo Submission Package) for Asphalt 9: Legends , version 4.0.2a , packed in RAR format. The Switch eShop automatically downloads the latest version