The modder, Demonslayerx8 or DSX8, is a prolific modder in the Smash Ultimate scene. Sorry for the trouble, it's been a long week figuring out these bugs and in the end the only solution was to revert new code that was made in preparation for one-slots back to how it was on version 1.0.1. Two leading game designers take readers step by step through the entire process of creating a video game, from developing a story and integrating it into a game, to writing the game script, creating the design document, working with.
To clear up the fear-mongering and misinformation spread throughout the Switch modding community regarding online activity with a modded Switch, please take a look through this GameBanana thread detailing what is safe and what isn't for both custom firmware usage and Super Smash Bros.