[allocator.adaptor.members] p9 says that the is_constructible tests are done using inner_allocator_type, which checks for construction from an rvalue, but then the constructor is passed inner_allocator() which returns a non-const lvalue reference. The value categories should be consistent, otherwise this fails to compile:

#include <memory>
#include <scoped_allocator>

struct X {
  using allocator_type = std::allocator<X>;
  X(std::allocator_arg_t, allocator_type&&) { }
  X(allocator_type&) { }
};

int main() {
  std::scoped_allocator_adaptor<std::allocator<X>> sa;
  sa.construct(sa.allocate(1));
}

uses_allocator<X, decltype(sa)::inner_allocator_type>> is true, because it can be constructed from an rvalue of the allocator type, so bullet (9.1) doesn't apply.

is_constructible<X, allocator_arg_t, decltype(sa)::inner_allocator_type> is true, so bullet (9.2) applies. That means we try to construct the object passing it sa.inner_allocator() which is an lvalue reference, so it fails.

The is_constructible checks should use an lvalue reference, as that's what's actually going to be used.

I don't think the same problem exists in the related wording in [allocator.uses.construction] if we assume that the value categories of v1, v2, ..., vN and alloc are meant to be preserved, so that the is_constructible traits and the initialization expressions match. However, it does say "an allocator alloc of type Alloc" and if Alloc is an reference type then it's not an allocator, so I suggest a small tweak there too.