Fix.

Author: WaVEV

django_mongodb_backend/fields/polymorphic_embedded_model_array.py

@@ -98,7 +98,7 @@ def __init__(self, key_name, array_field, *args, **kwargs):
         # Lookups iterate over the array of embedded models. A virtual column
         # of the queried field's type represents each element.
         column_target = field.clone()
-        column_name = f"${self.PREFIX_ITERABLE}.{key_name}"
+        column_name = f"$item.{key_name}"
         column_target.db_column = column_name
         column_target.set_attributes_from_name(column_name)
         self._lhs = Col(None, column_target)