Proposed resolution:

Change the synopsis of [func.wrap.func], and remove the associated definitions in [func.wrap.func.con]:

template<Returnable R, CopyConstructible... ArgTypes> 
class function<R(ArgTypes...)>
{
    ...
    template<class F> 
      requires CopyConstructible<F> && Callable<F, ArgTypes...> 
            && Convertible<Callable<F, ArgTypes...>::result_type, R> 
      function(F); 
    template<class F> 
      requires CopyConstructible<F> && Callable<F, ArgTypes...> 
            && Convertible<Callable<F, ArgTypes...>::result_type, R> 
      function(F&&);
    ...
    template<class F, Allocator Alloc> function(allocator_arg_t, const Alloc&, F); 
    template<class F, Allocator Alloc> function(allocator_arg_t, const Alloc&, F&&);
    ...
    template<class F> 
      requires CopyConstructible<F> && Callable<F, ArgTypes..> 
            && Convertible<Callable<F, ArgTypes...>::result_type 
      function& operator=(F); 
    template<class F> 
      requires CopyConstructible<F> && Callable<F, ArgTypes...> 
            && Convertible<Callable<F, ArgTypes...>::result_type, R> 
      function& operator=(F&&);
    ...
};