create_new_manager_class_from_as_manager_method : TypeVar QuerySet does not seems to work.

[MoranAbadieGatewatcher]

Bug report

I have the following code (this is a simplified version of my problem):

from typing import TypeVar, TYPE_CHECKING
from typing_extensions import Self

from django.db import models

_CTE = TypeVar("_CTE", bound=models.Model)

class _MyModelQuerySet(models.QuerySet[_CTE]):

    if TYPE_CHECKING:
        def example(self) -> _CTE: ...
    
    def test(self) -> "Self":
        return self

class MyModelQuerySet(_MyModelQuerySet["MyModel"]):
    pass

class MyModel(models.Model):
    objects = MyModelQuerySet.as_manager()


def use_my_model():
    foo: MyModel = MyModel.objects.example() # error (1)
    foo2: int = MyModelQuerySet().example()  # error (2)
    MyModel.objects.test().example()   # error (3)

I have the mypy report :

(1) error: Incompatible types in assignment (expression has type "_CTE", variable has type "MyModel") [assignment]
(2) error: Incompatible types in assignment (expression has type "MyModel", variable has type "int") [assignment]
(3) error: <nothing> has no attribute "example"
The (2) is right, but the (1) is wrong.

Moreover Self types seems not to work (with (3))

What's wrong

It seems that when ManagerFromMyModelQuerySet is created, it does not work with a TypeVar, nor Self type.

System information

OS: Ubuntu
python version: 3.9.10
django version: 3.2.19
mypy version: 1.4.1
django-stubs version: 4.2.3
django-stubs-ext version: 4.2.2