Question: How to bound a mixin to a subclass

I created a mixin for Django models and I would like to know how to properly type it, e.g.:

from django.db import models

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


class SafeCreateMixin:
    @classmethod
    @transaction.atomic()
    def safe_create(cls: Type[T], **kwargs) -> Optional[T]:
        try:
            return cls.objects.create(**kwargs)
        except IntegrityError as e:
            return None

class MyModel(SafeCreateMixin, models.Model):
    ....

It fails with the following error:

error: The erased type of self "Type[django.db.models.base.Model]" is not a supertype of its class "Type[SafeCreateMixin]"

I understood that the mypy docs recommend creating a Protocol for mixins, but in my case, I just want to enforce that my mixins are added to a subclass of models.Model

Start by reproducing the reported error with the SafeCreateMixin and MyModel example, then read the mypy documentation on mixins and Protocols. Determine whether the requested subclass constraint is supported or needs a design decision; done means the behavior and recommended approach are clearly established.