Loss of smoothness of a MeshViz/Makie plot when assigning colors to vertices

I have a 3D mesh made with the Meshes package. When I plot it with MeshViz using the default attributes, it is smooth. But when I assign some colors to the vertices of the mesh, it is not smooth anymore:

How to have the smoothness? This plot looks like a 3D plot obtained when we don’t provide the normals.

Ah it is nice when I triangulate the mesh!