Proposed resolution:

Change [allocator.element.concepts]:

template <Allocator Alloc, class T, class ... Args>
  requires HasConstructor<T, Args...>
    concept_map AllocatableElement<Alloc, T, Args&&...> {
      void construct_element(Alloc& a, T* t, Args&&... args) {
        Alloc::rebind<T>(a).construct(t, forward(args)...);
      }
    }