For some reason, I get a broken access_token in return when  I’m trying to make a user authentication through my .net code.
Strangely, the exact same call in POSTMAN works like a charm.
In essence, the broken access_token returned contains 3 dots like ‘…’ somewhere in token rendering it invalid (verified through jwt.io).
Note, that the json has not been truncated since it actually looks complete.
And the HttpStatusCode == OK
The c# code looks like this:
            Dictionary<string, string>? dict = new() {
                { "audience", audience },
                { "grant_type", "password" },
                { "username", username },
                { "password", password },
                { "client_id", clientId },
                { "client_secret", clientSecret }
            };
            
            string payload = JsonConvert.SerializeObject(dict);
            HttpRequestMessage? req = new(HttpMethod.Post, url) { Content = new StringContent(payload, Encoding.UTF8, "application/json")};
            HttpResponseMessage? res = await _httpClient.SendAsync(req);
            string result = await res.Content.ReadAsStringAsync();
            return new (result, res.IsSuccessStatusCode );
The Postman call looks like this:
POST {myurl}
Content-Type: application/json
{
    "client_id": "{my client_id},
    "client_secret": "{my_client_secret}",
    "audience": "{my_audience_in_api},
    "username": "{my_username}",
    "password": "{my_password}",
    "grant_type": "password"
}
