Sendinblue API integration

The integration between CF7 and Sendinblue is working pretty well besides the opt_in flag.

Here you can see the CF7 backend:

<script>
document.addEventListener( 'wpcf7mailsent', function( event ) {
  location = 'https://caniaspasso.it/grazie/';
}, false );
</script>

<label> Il tuo nome
    [text your-nome] </label>

<label> La tua email (richiesto)
    [email* your-email] </label>

<label> Il tuo numero di telefono (richiesto)
[intl_tel* your-sms initialCountry:it]</label>

<label> Servizio scelto (richiesto)
    [select* servizio-scelto include_blank "Dog sitter" "Educazione" "Wedding dog sitter"] </label>

<label> Il tuo messaggio
    [textarea your-message] </label>

[acceptance your-optin optional consent_for:sendinblue]
Aggiungimi alla tua lista di contatti.
[/acceptance]

[submit "Invia"]

in here you can see the frontend part:

I edited the contacts attribute from OPT_IN to OPTIN in Sendinblue but still, If I submit the form, no OPTIN data is displayed on Sendinblue panel.

Beside your documentation https://contactform7.com/sendinblue-integration/#contact-attribute-form-field-mapping , I found nothing else on Internet.

Do you have any help/advice?

The page I need help with: [log in to see the link]