RPITIT causes incorrect "dropped while still borrowed" error in some cases

From this SO question, the following code does not compile:

trait Iterable {
    fn owned_iter(&self) -> impl Iterator<Item = usize> + 'static;
}

struct B<T> {
    x: T,
}

impl<T: Iterable + Clone> Iterable for B<T> {
    fn owned_iter(&self) -> impl Iterator<Item = usize> + 'static {
        let y = self.x.clone();
        y.owned_iter() // error[E0597]: `y` does not live long enough
    }
}

However, boxing the iterator as a trait object allows it to compile:

trait Iterable {
    fn owned_iter(&self) -> impl Iterator<Item = usize> + 'static;
}

struct B<T> {
    x: T,
}

impl<T: Iterable + Clone> Iterable for B<T> {
    fn owned_iter(&self) -> impl Iterator<Item = usize> + 'static {
        let y = self.x.clone();
        let b: Box<dyn Iterator<Item = usize>> = Box::new(y.owned_iter());
        b
    }
}

Notably, not cloning self.x and simply returning self.x.owned_iter() also works.

I don't see any reason why the first code block shouldn't compile, especially while the boxed version and the non-cloning version do.

Meta

rustc --version --verbose:

rustc 1.81.0 (eeb90cda1 2024-09-04)
binary: rustc
commit-hash: eeb90cda1969383f56a2637cbd3037bdf598841c
commit-date: 2024-09-04
host: x86_64-unknown-linux-gnu
release: 1.81.0
LLVM version: 18.1.7

It also fails to compile on 1.83.0-nightly (2024-10-09 eb4e2346748e1760f74f).

Start by compiling the two provided Rust reproductions with the reported stable and nightly toolchains, then compare the cloned, boxed, and non-cloning cases and their E0597 diagnostics. No source file or existing test is identified in the issue; done means the first example is accepted consistently with the working variants, with a regression test covering the behavior.