Use NSC Builder or SAK (Switch Army Knife) to check the integrity of the 3.0.3 NSP. Look for:
This release, labeled “RAWR Work,” provides the official Update 3.0.3 for Mario Kart 8 Deluxe in a pre-packaged NSP format. The update is intended for use with custom firmware environments (Atmosphere, Ryujinx, Yuzu) and has been verified to be fully functional (“RAWR Work” indicating a clean, working dump with no corruption or missing tickets). mariokart8deluxeupdate303nsprar work
Platform: Nintendo Switch
File Type: NSP (Nintendo Submission Package)
Release Name: Mario Kart 8 Deluxe [Update v3.0.3] [NSP] [RAWR Work]
Region: Unlocked / Multi Use NSC Builder or SAK (Switch Army Knife)