It looks very similar to the Mario Kart GP Diamond City course, so I'm assuming they remade the entire stage or based it around that one structure alone. Hopefully this could mean that a Wario character is coming to Tour as well.
I assume it's a stage parodying Bowser's Japanese castle from Odyssey, but it could also be a reference to Wario Land Shake it. It's a shame Wario's Stadium from N64 will never be remastered.