I have two fields inheriting from the Wagtail Page models, such as:
class ModelA(Page):
    custom_field = models.CharField(max_length=255)
    search_fields = Page.search_fields + [
        index.SearchField("custom_field")
    ]
class ModelB(Page):
    custom_field = models.CharField(max_length=255)
    search_fields = Page.search_fields + [
        index.SearchField("custom_field")
    ]
I am using the Wagtail database search backend, with Postgres as my DBMS:
WAGTAILSEARCH_BACKENDS = {
    "default": {
        "BACKEND": "wagtail.search.backends.database",
    }
}
I would like to make a query from the Page class that traverses the Page model to find results from both ModelA and ModelB:
search_results = Page.objects.filter(custom_field="some value")
However, The above example throws an error:
django.core.exceptions.FieldError: Cannot resolve keyword 'custom_field' into field.
How can I search for values in custom_field across multiple models inheriting from the Wagtail Page model?