EmbeddedDocumentListField default value issue

There's a EmbeddedDocumentListField ("Radios") that has default values: [Radio(), Radio()], the default value definition is modified after the data been stored in database so there's no value in database.

While get the EmbeddedDocumentListField default value everything is fine, but there's something wrong when update some value of the default value in the List.

radio = network.radios.get(type=xxx)
radio.is_enable = True
network.save()

Database wrong data:
"radios": {
   "0": {
       "is_enable": true
   }
} 

Start by reproducing the EmbeddedDocumentListField default-value case with [Radio(), Radio()] and the shown network.save() update. Inspect how the default list is loaded and persisted, then verify that changing a nested Radio value stores the complete embedded list rather than the malformed "radios": {"0": ...} shape.