Amplified World Type Generating in Regular Worlds

The world seems to be generating like an Amplified world-type dispite it being a regular Multiplayer map.

Seed: 4929779908565412268 Coords: x=4212 y=147 z=-1971

It's in a Savannah Plateau M biome. Lots of floating blocks and extreme Y changes. There are a few places where blocks generate past y=200. A ton of Grassless Dirt and naked Stone also generates here.