@Belgiumfan777 They had to update the game to add support for the new Sora amiibo releasing this month, so someone (possibly Sakurai) decided to add new spirits to celebrate the 5th Anniversary. There's a total of 4 events and this is the third one.
First event had 4 first party games: The Legend of Zelda: Tears of the Kingdom, Xenoblade Chronicles 3, Pikmin 4, and Splatoon 3, each with one new spirit.
Second event had 3 third party games:
WBSC eBASEBALL: POWER PROS, 13 Sentinels: Aegis Rim, and Hades, each with one new spirit.
And the third event is all about Pokémon Scarlet and Violet because there's a lot you can do with Pokémon spirits.
The fourth event is almost certainly going to include Super Mario Bros. Wonder, but I don't know if the event will focus solely on it or if it will be multiple games again. Other games they could do include Kirby and the Forgotten Land (Elfilin) and Fire Emblem Engage (Alear).