I am unable to update value of lifecycle stage using hubspot api

Question

I am using hubspot api to update the value of lifecycle stage of a contact. The value can be changed to any other value in the hubspot crm. But when I am using the api to do so, I can change the value of the lifecycle stage to a higher stage say, from a Subscriber to Lead, as Subscriber is lower in rank than Lead. But when I try to change the value from Lead to Subscriber using the api, it doesn't do so. There is no error too. I am not sure if it is a bug with the api or there is some restriction to do so.

The code for my api:

def update_contact_lifecycle_stage(request , *args):
    try:
        api_client = HubSpot(access_token=HUBSPOT_API_KEY)

        #get this from params
        contact_email = "[email protected]"


        filter_query = { "propertyName": 'email', "operator": 'EQ', "value": contact_email }
        filterGroup = {
            "filters" : [filter_query]
        }

        search_request = PublicObjectSearchRequest(
            filter_groups= [filterGroup],
            properties=['vid']
            )
        
        response = api_client.crm.contacts.search_api.do_search(public_object_search_request=search_request)

        contacts = response.results

        if contacts:
            contact_vid = str(contacts[0].id) 

            #Get this from params
            new_lifecycle_stage = "subscriber"
            contact_update = {
                "lifecyclestage": new_lifecycle_stage 
            }

            simple_public_object_input = SimplePublicObjectInput(
                properties=contact_update)

            try:
                api_response = api_client.crm.contacts.basic_api.update(
                    contact_vid,
                    simple_public_object_input=simple_public_object_input
                )
                

            except ApiException as e:
                print(f"HubSpot API error: {e}")

    except Exception as e:
        print(f"An error occurred: {e}")