Why does the shape of the dwarf planet Haumea appear as being like a rugby ball?

Astronomers believe Haumea has its rugby ball shape because it rotates so fast. The dwarf makes one revolution in just 4 hours! Haumea's size and distance away from Earth make it impossible to see details of Haumea's shape, however, due to the way it reflects light scientists have come up with the rugby ball shape. The dwarf planet is part of the Kuplier belt and is about 1/4 the mass of Pluto. A year on Haumea takes 283 Earth years to revolve around the sun making it have approximately 620,194 days in a year!

https://www.schoolsobservatory.org/learn/astro/solsys/dwarfs/haumea