Exception on delete of polymorphic collection

[unusual-thoughts]

class Order(models.Model):
    title = models.CharField(_("Title"), max_length=200)

    class Meta:
        ordering = ('title',)

    def __str__(self):
        return self.title

class Payment(PolymorphicModel):
    order = models.ForeignKey(Order, on_delete=models.CASCADE)
    amount = models.DecimalField(default=0, blank=True, max_digits=10, decimal_places=2)
    index = models.PositiveIntegerField(default=0, blank=False)

    class Meta:
        ordering = ('index',)

class CreditCardPayment(Payment):
    card_type = models.CharField()

class Beneficiary(models.Model):
    firstname = models.CharField()
    lastname = models.CharField()

class SepaPayment(Payment):
    iban = models.CharField()
    bic = models.CharField()
    beneficiaries = models.ManyToManyField(Beneficiary, "sepa", blank=True)

When deleting an Order whose first Payment is of type SepaPayment, an exception is raised :
Exception Value: Cannot query <CreditCardPayment>: Must be "SepaPayment" instance.

This is because of this code in django core: https://github.com/django/django/blob/master/django/db/models/deletion.py#L193

The model type is taken from the first element in the polymorphic collection

Minimal example here: https://github.com/unusual-thoughts/django-poly-bug

[PierreMDL]

I'm getting the same error, years after this (Django 5.2, django-polymorphic 4.1.0). Did you manage to fix it or find a workaround?

Note that it doesn't seem to be a cascading problem from Order. Payment.objects.all().delete() would throw the same error. I think it's because of the ManyToMany fields on subclasses.
The PolymorphicQuerySet does not re-implement .delete(), where the problem happens with the Collector.