If a pointer p whose static type is “pointer to class B” is pointing to an object of class D, derived from B, the dynamic type of the expression *p is “D”.

In normal, according to the pointer conversion, a static type of “pointer to class B” is pointing to the base class subobject B rather than the complete object D. The implication of the note would result in the misreading to [expr.unary.op] p1

the result is an lvalue referring to the object or function to which the expression points.

The note may be clear if we say

If a pointer p whose static type is “pointer to class B” is pointing to the base class B subobject of class D, derived from B, the dynamic type of the expression *p is “D”.