The NSP (Nintendo Submission Package) is a format used for digital distribution of games on the Nintendo Switch. The "fixed" NSP version of Pikmin 4 means that players can now enjoy the game without encountering issues related to the NSP format, such as installation problems or corrupted data.
He played for an hour, but the "fixed" game felt a little broken to him. The next morning, he walked down to the local game shop and traded in three old titles he didn't play anymore. He walked out with a physical cartridge—no "fix" required.
For those using modified hardware to install updates manually: The Pikmin 4 Update has Been Fixed! (kinda)