Property for mesh vertex

I’m trying to assign a property to mesh vertices.
It works with meshes and not works with vertices.

import bpy

class PROP_cls(bpy.types.PropertyGroup):
    prop1: bpy.props.IntProperty(default=1)

bpy.utils.register_class(PROP_cls)
bpy.types.Mesh.prop1 = bpy.props.PointerProperty(type=PROP_cls)
print(bpy.context.object.data.prop1)

bpy.types.MeshVertex.prop2 = bpy.props.PointerProperty(type=PROP_cls)
print(bpy.context.object.data.vertices[0].prop2)

output:
<bpy_struct, PROP_cls("")>
((built-in function PointerProperty),(‘type’: {class ‘main.PROP_cls’}))

Why it differs?
And how to assign a custom propertyes to vertices?