Python Elastic Reindex : failed to parse field [source]

I am trying to reindex an index with python with the following function

resp = client.reindex(
        body={
            "source": {
                "remote": {"host": "url_name:9200","username": "elastic","password": "password"},
                "index": "whateverindex",
                "query": {"match_all": {}}
            },
            "dest": {"index": "whateverindex"}
        }
    )

And I am getting

BadRequestError(400, 'x_content_parse_exception', '[1:217] [reindex] failed to parse field [source]')

I've been trying to understand how come does elastic can't parse the source. It's a snippet of code that I took and modified a little (added user/password) from the official documentation.

Am I missing something ?

EDIT :

Code using the source and dest parameters as Val stated in the comments :

resp = client.reindex(
    source={
            "remote": {"host": "waked-kibana.cws.cines.fr:9200","username": "elastic","password": "VBcpxfR*HgMAs6-nf*4c"},
            "index": "covid19_api_arxiv_2012",
            "query": {"match_all": {}}
            }, 
    dest = {"index": "covid19_api_arxiv_2012"})

Still have a parseing error on Source.