Nintendo had confirmed a few days ago that Super Smash Bros. Ultimate would be getting an update soon, so it was expected. That said, the update has just been released, bringing the game to version 6.1.0. Although the patch notes aren’t on Nintendo’s website as of this post’s writing, an in-game notice was posted that had them. However, the only thing the patch notes says is that “a rare issue has been fixed when Terry’s Super Special Move “Buster Wolf” connects with an opposing fighter, causing both Terry and that fighter to become unable to move from their positions.
Source: Smash Ultimate In-Game Notice