While 3.0.1 is a "hotfix" patch, it maintains the massive features added in the 3.0.0 milestone:

Fixed a "floating" glitch where players driving off-course were not properly retrieved by Lakitu .

Appendix:

When you see an NSP file, you are looking at a digital "eShop" version of the game. Unlike cartridge dumps (XCI files), NSPs are generally smaller and easier to install on modded Switch consoles (or emulators like Ryujinx and Yuzu). The fact that you have the (Update) in NSP format means you have a standalone patch file that can be installed over a base game to transform it into that specific version.

Multiplayer & online:

Have you ever been in 8th place on the final lap of Neo Bowser City and pulled a single Banana? Infuriating, right? Patch 3.0.1 subtly adjusts the distance-based item probability. Drivers in the bottom three positions will now see slightly more Bullet Bills and Shock Drops slightly earlier. This doesn't break the game, but it closes the "hopeless gap" on 200cc.