Early versions of the game suffered from significant issues, including:

Even with a "Fixed" file, Age of Calamity remains one of the most demanding games on the Switch architecture.

How to Update Hyrule Warriors: Age of Calamity | Nintendo Switch

In the homebrew scene, an (Nintendo Submission Package) is a digital file format for Switch software. When Age of Calamity leaked prior to its official 2020 release, early NSP files often failed to boot on older custom firmware (CFW) due to mismatched "sigpatches" (signature patches) or requiring a higher system firmware than what users had installed.

For those using PC-based emulators, the "fixed" versions were often a necessity. These files allowed for better compatibility with shaders, enabling players to experience the Great Calamity at higher resolutions and more stable frame rates than the native hardware could provide at the time. A Note on Stability

Here are a few extra bits to make the narrative richer:

hyrule warriors age of calamity nsp fixed