Error when authenticating with Default Azure Credential (CSOM)

Before the summer break I used a code that we have developed to set up content on SharePoint sites though local host when running from Visual Studio. Then when I returned about a week later the code failed with the following error message and reasoning:

The remote server returned an error: (401) Unauthorized.
Reason: App is not allowed to call SPO with user_impersonation scope

No changes where made to the code.

The authentication code is implement as this:

public async Task<ClientContext> GetClientContextAsync(Uri siteUri)
{
    try
    {
        var accessToken = await GetAccessTokenAsync(siteUri.Host);
        var authManager = new AuthenticationManager();

        return authManager.GetAccessTokenContext(siteUri.ToString(), accessToken.Token);
    }
    catch (Exception ex)
    {
        logger.Error(string.Format("GetClientContextAsync (Token): {0}", ex.Message));
        return null;
    }
}

private async Task<AccessToken> GetAccessTokenAsync(string siteUrl)
{
    DefaultAzureCredential credential = new DefaultAzureCredential();
    String scope = $@"https://{siteUrl}/.default";
    AccessToken accessToken = await credential.GetTokenAsync(new TokenRequestContext(new[] { scope }));

    return accessToken;
}

Has it been any changes to the authentication method?