c++ coroutine, done() function returns different value in a same loop

godbolt: https://godbolt.org/z/6avWcGqKv

The following code, compiled and run with g++ 12, 13, 14, all give the same (wrong?) output.

clang 18, 19 are fine (all "done: 1").

As far as I understand, since the initial_suspend() is suspend_never, after creation, the promise runs immediately to final_suspend, and should return "true" when querying "done()", but one of them does not. Is it my programming error, or compiler error, or some UB, or something?

Program returned: 0
done: 1
done: 1
done: 1
done: 1
done: 1
done: 0  <-- ???
done: 1
done: 1
done: 1
done: 1

code:

#include <coroutine>
#include <iostream>
#include <vector>

struct Task {
  struct promise_type {
    Task get_return_object() {
      return {.h = std::coroutine_handle<>::from_address(this)};
    }
    std::suspend_never initial_suspend() noexcept { return {}; }
    std::suspend_always final_suspend() noexcept { return {}; }
    void unhandled_exception() {}
    void return_void() {}
  };
  std::coroutine_handle<> h;
};

Task coro() { co_return; }

int main() {
  std::vector<Task> v;
  for (int i = 0; i < 10; ++i)
    v.push_back(coro());
  for (auto &t : v)
    std::cout << "done: "<< t.h.done() << "\n";

  return 0;
}