The firmware (HOS) is too old for the update requirements. Fix: v1.1.0 requires HOS 14.1.2 or higher. Update your Switch firmware using Daybreak.
Mandatory for online play and matching with other updated players. Compatible with save data from previous versions. Gameplay Overview: Battle with Your Team Super Kirby Clash Switch NSP UPDATE
In a "homebrew" or preservation context (managing NSPs manually), the process involves: The firmware (HOS) is too old for the update requirements