Why? Callee-borrowing-from-caller is the established norm across the C API. You mention use-after-free, but can you elaborate on how that can happen in practice?

https://docs.python.org/3/extending/extending.html?highlight=borrowed#ownership-rules says:

"""When you pass an object reference into another function, in general, the function borrows the reference from you — if it needs to store it, it will use Py_INCREF() to become an independent owner."""