Intermittent ExchangeException when getting EWS mail folders using GetEWSClient in Aspose.Email

I have a Windows service that uses Aspose.Email to call Exchange365 using EWS to read the list of mailbox folders, select a folder and then read the messages. I'm using OAuth Client Credentials authentication.

It works great most of the time but intermittently (around 1-2% of calls) I get an error like this:

ExchangeException: An internal server error occurred. The operation failed.
   at #=zJwR5hYhASPjEG51KcFP5cfaNW_E9xKzbKNrDvkouRDML.#=zbEiudxU=(Exception #=zXBxojZA=)
   at #=zJwR5hYhASPjEG51KcFP5cfaNW_E9xKzbKNrDvkouRDML.#=zJxs8Enk=()
   at Aspose.Email.Clients.Exchange.WebService.EWSClient.#=zeKhM5WV7jZFJ(String #=zwl3m1OEGe_npeTCLKA==, ICredentials #=z8dcYagA=, WebProxy #=zPxR7k20=, #=zobHVK5XZznS2TuzCjFYVkWlb_06X8KyvTg== #=zuLDkIL8cyRRE, #=zLSBmP6s5p40Nd06_7HFvrX6K9S$RdU6i23eiqR0t6nn3VKSIig== #=zPNhWaZtYKy02YJZNn6uibe8=)
   at Aspose.Email.Clients.Exchange.WebService.EWSClient.GetEWSClient(String mailboxUri, ICredentials credentials, WebProxy proxy)
   at Aspose.Email.Clients.Exchange.WebService.EWSClient.GetEWSClient(String mailboxUri, ICredentials credentials)
   at EmailTest.Program.GetFolders(OAuthNetworkCredential credentials) in C:\Dev\Sandbox\EmailTest\Program.cs:line 72
   at EmailTest.Program.<Main>d__0.MoveNext() in C:\Dev\Sandbox\EmailTest\Program.cs:line 42

or

ExchangeException: An internal server error occurred. The operation failed.
   at #=zRSjcm9RrA3a6zmmitFu34UW3nW4gV823KL6N1k9mXXhY.#=zqfYcQSUW7xkI(WebException #=zMMH$jH0=)
   at #=zRSjcm9RrA3a6zmmitFu34UW3nW4gV823KL6N1k9mXXhY.GetResponse()
   at System.Web.Services.Protocols.WebClientProtocol.GetWebResponse(WebRequest request)
   at System.Web.Services.Protocols.HttpWebClientProtocol.GetWebResponse(WebRequest request)
   at System.Web.Services.Protocols.SoapHttpClientProtocol.Invoke(String methodName, Object[] parameters)
   at #=zKdOmVOFQs9ARtLG3Zlu_IvXd08LXFmI3_5D9s_gr4KsZjsevGw==.FindFolder(FindFolderType FindFolder1)
   at #=zKdOmVOFQs9ARtLG3Zlu_ImWGLEjOliBGtOJU8_WNO6d9X7U9LuJoRwA=.#=zthDK7XA=(BaseFolderIdType #=zW0dJQvKwqFVf, String #=z7p_vI0c=)
   at #=zKdOmVOFQs9ARtLG3Zlu_ImWGLEjOliBGtOJU8_WNO6d9X7U9LuJoRwA=.#=zthDK7XA=(String #=zxohf2Vezm7Vf, String #=z$vyJZib10Ez_, String #=z7p_vI0c=)
   at #=zTAbjhrGUH9E0n8cOeUNrQiqgnbUhJNI_gUj7wuZ$HYDp.ListSubFolders(String #=zxohf2Vezm7Vf, String #=znaKuRg4Rx3vw)
   at #=zTAbjhrGUH9E0n8cOeUNrQiqgnbUhJNI_gUj7wuZ$HYDp.ListSubFolders(String #=znaKuRg4Rx3vw)
   at EmailTest.Program.GetFolders(OAuthNetworkCredential credentials) in C:\Dev\Sandbox\EmailTest\Program.cs:line 74
   at EmailTest.Program.<Main>d__0.MoveNext() in C:\Dev\Sandbox\EmailTest\Program.cs:line 42

If I retry the failing call immediately afterwards, it works fine. So as a workaround I use a "retry" pattern with this call, but I don't like this and I want to know why it's failing. I made a cut-down version of my code for investigation purposes.

Here is how I'm creating the credentials:

private static async Task<OAuthNetworkCredential> GetAccessTokenWithClientCredentials()
{
    var app = ConfidentialClientApplicationBuilder
        .Create(Settings.ClientId)
        .WithTenantId(Settings.TenantId)
        .WithClientSecret(Settings.ClientSecret)
        .Build();

    AuthenticationResult authResult =
        await app.AcquireTokenForClient(new[] { Settings.Scopes }).ExecuteAsync().ConfigureAwait(false);
    return new OAuthNetworkCredential(Settings.Username, authResult.AccessToken);
}

and here's how I'm calling the folders:

private static string GetFolders(OAuthNetworkCredential credentials)
{
    using (IEWSClient client = EWSClient.GetEWSClient(Settings.ExchangeWSUrl, credentials))
    {
        ExchangeFolderInfoCollection folders = client.ListSubFolders(client.MailboxInfo.RootUri);
        return string.Join(", ", folders.Select(x => x.DisplayName));
    }
}

This is using Aspose.Email 22.8 and Microsoft.Identity.Client 4.46.2.
ExchangeWSUrl is https://outlook.office365.com/ews/exchange.asmx
Scopes is https://outlook.office.com/.default