According to the official patch notes, Update 1.1.1 for Super Mario Party includes several improvements and bug fixes. Here are some of the key changes:
While the update itself is official from Nintendo, files shared in this compressed format are often found on community-run repositories for users who may be managing their software libraries manually. How to Update Officially
Here’s an regarding the file Super-Mario-Party-Jamboree-Update-1.1.1.NSP.rar .
But the presence of this filename on the open web highlights a persistent issue for Nintendo: their games are popular, but their security is constantly under siege. Within days of a major release, the "Scene" (the underground community of software crackers) has usually ripped, packed, and distributed the game. Jamboree was no exception, appearing online almost instantly after its retail release.
: General stability improvements to ensure smoother online play. Technical & Compatibility Notes