It was the best of box arts, it was the worst of box arts. When the cover art for Fire Emblem: Three Houses was first revealed, one thing immediately jumped out: one of the main characters was upside down.
This is, of course, Claude. The incredibly hot leader of the Golden Deer was upside down on the front cover of the game… for some reason. Nobody really knows why Claude was tilted, but it became one of the best running jokes in the Three Houses community.
It seems Masahiro Sakurai and the team behind Super Smash Bros. Ultimate are well aware of the joke. When you go to claim Claude's spirit from the Spirit Board in Super Smash Bros. Ultimate, the controls are periodically flipped, so that right is left, and left is right.
This appears to be a homage to the flipped nature of Claude on the cover. The reason this level probably isn't flipped vertically is that there isn't an ability in the game that would do that, whereas there is a feature that flips the controls around. It's a great little nod to the cover of Three Houses, and I love that guest characters in Smash Bros. are treated with so much attention to detail.
If you're looking for a complete breakdown of how the latest fighter to join Super Smash Bros. Ultimate plays, head over to our Byleth guide. There's a full moves list and controls on the page, and much more to delve into.