impl Trait in return position implicitly captures non-`'static` type parameter despite `+ 'static`

Code

trait MyTrait {}
struct MyStruct;
impl MyTrait for MyStruct {}

trait DeserTrait<'de> {}
struct DeserStruct;
impl<'de> DeserTrait<'de> for &'de DeserStruct {}

pub fn testfn<'de, D: DeserTrait<'de>>(_deserializer: D) -> impl MyTrait + 'static {
    MyStruct
}

fn test() -> impl Send {
    let deserializer = DeserStruct;
    let graph = testfn(&deserializer);
    graph
}

(playground)

Current output

error[E0597]: `deserializer` does not live long enough
  --> src/lib.rs:15:24
   |
14 |     let deserializer = DeserStruct;
   |         ------------ binding `deserializer` declared here
15 |     let graph = testfn(&deserializer);
   |                 -------^^^^^^^^^^^^^-
   |                 |      |
   |                 |      borrowed value does not live long enough
   |                 argument requires that `deserializer` is borrowed for `'static`
16 |     graph
17 | }
   | - `deserializer` dropped here while still borrowed

Desired output

I'm not sure, but adding + use<> to the function's return type explains what the issue is actually that impl Trait implicitly captured the trait bound:

error: `impl Trait` must mention all type parameters in scope in `use<...>`
 --> src/lib.rs:9:61
  |
9 | pub fn testfn<'de, D: DeserTrait<'de>>(_deserializer: D) -> impl MyTrait + use<> + 'static {
  |                    -                                        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  |                    |
  |                    type parameter is implicitly captured by this `impl Trait`
  |
  = note: currently, all type parameters are required to be mentioned in the precise captures list

Rationale and extra context

It's impossible to debug (or google) otherwise, and I only figured it out because I remembered + use<> from the stabilization blog post

Other cases

No response

Rust Version

rustc 1.82.0

Anything else?

No response

Start with the playground reproduction linked in the issue and compare rustc 1.82.0's diagnostic for the testfn return type with the proposed + use<> diagnostic. Trace the compiler's handling of implicit impl Trait captures and diagnostic emission; done means the reported error clearly identifies the implicitly captured parameter without regressing related cases.