The following script:

from collections.abc import Iterable, Iterator


class A(Iterable):
    _list: list[int]

    def __init__(self, *args: int) -> None:
        self._list = list(args)

    def __iter__(self) -> Iterator[int]:
        return iter(self._list)


a = A(1, 2, 3)

for i in a:
    reveal_type(i)

for s, j in zip("abc", a):
    reveal_type(j)

yields the following mypy output:

$ mypy test.py
test.py:17: note: Revealed type is "builtins.int"
test.py:20: note: Revealed type is "Any"
Success: no issues found in 1 source file

Why is the type Any when iterating on zip, but not on the object directly?