I am using Azure B2C for authentication in my .NET Core web api project. I am trying to renew refresh token using step outlined in documentation – https://learn.microsoft.com/en-us/azure/active-directory-b2c/authorization-code-flow#4-refresh-the-token.

The request parameters (using RestSharp) I am sending are below:

var request = new RestRequest();
request.Method = Method.Post;
request.AddHeader("content-type", "application/x-www-form-urlencoded");
request.AddParameter("grant_type", "refresh_token", ParameterType.GetOrPost);
request.AddParameter("client_id", CLIENT_ID_HERE, ParameterType.GetOrPost);
request.AddParameter("scope", "CLIENT_ID_HERE offline_access", ParameterType.GetOrPost);
request.AddParameter("refresh_token", OLD_REFRESH_TOKEN, ParameterType.GetOrPost);

I am getting success response, as shown below:

{
    "access_token":"eyJhbGciOiJSUzI1NiIsImtp......",
    "id_token":"eyJhbGciOiJS......",
    "token_type":"Bearer",
    "not_before":1720104657,
    "expires_in":3600,
    "expires_on":1720108257,
    "resource":"guid-here",
    "id_token_expires_in":3600,
    "profile_info":"eyJ2ZXIiO.........",
    "scope":"B2C_Client_Id offline_access openid",
    "refresh_token":"eyJraWQiOiJjcGltY29yZ...........",
    "refresh_token_expires_in":76887
}

Few response parameters – refresh_token_expires_in, expires_on, etc are not mentioned in the documentation.

Now, with respect to json response, I have few confusions/doubts:

1. The default refresh token expiry is 14 days and can be extended to 90 days. But. the value in refresh_token_expires_in is in seconds not in unix timestamps. Is that even correct?
2. The value in expires_on is a unix timesteamp and translates to 54 days. What could be expiring here?

Any thoughts?