Application Python for OIDC connexion

Question

I meet a problem and I search a solution, can you help me? I make an Python application for test a OIDC connection with PKCE. I can authenticate myself and have a personnal message like "Hello Name_user" thanks the ID Token. Now my goal is to implement the PKCE. The IDP is configure and my application too, but it doesn't work. I tried to troubleshooting by reading all the documentation on the Net but nothings.

In my IDP, he's configure to put the PKCE and in my application I have write this in my login part :

   "code_verifier = pkce.generate_code_verifier(length=128)
    code_challenge = pkce.get_code_challenge(code_verifier)

    nonce = 'generate_a_nonce_value_here'
    session['nonce'] = nonce
    session['code_verifier'] = code_verifier
    redirect_uri = 'http://127.0.0.1:5000/auth'
    session['redirect_uri'] = redirect_uri

    authorize_params = {
        'nonce': nonce,
        'client_id': client_id,
        'redirect_uri': redirect_uri,
        'response_type': 'code',
        'scope': 'openid id',
        'code_challenge': code_challenge,"

and write this in my auth part : "code = request.args.get('code') code_verifier = session['code_verifier']

    # Obtenir l'access token
    token_response = requests.post(
        token_url,
        data={
            'code': code,
            'code_verifier': code_verifier,
            'grant_type': 'authorization_code',
            'redirect_uri': session['redirect_uri'],
            'client_id': 'client_id_of_my_idp',
            'client_secret': 'secret_key_of_my_idp',
            'scope': 'openid id id2 id3'
        },
        verify=False
    )"

I generated of random way my code_verifier and I tried most test I have found on the internet. To finish, when I authentificate myself, I have my personnal message and in the logs of IDP I don't have a error or other. The IDP just say "Generated token OK: code in authorization code flow" even though everything is set up for PKCE