400 error while accessing ExchangeService through Microsoft Graph

I am facing a wired problem and not able to figure out the solution. Any suggestions/solutions on this will be much appreciated. Thanks in advance.
Context: The request failed. The remote server returned an error: (400) Bad Request.
C# App is throwing an error with the above message while instance/object of the ExchangeService is Calling GetRoomLists method.

Details: The aim is to get the list of Rooms associated with specific user belongs to a corporate Exchange Server. To achieve the purpose, following code snippets are written

    var cca = ConfidentialClientApplicationBuilder
                        .Create("*******")
                        .WithClientSecret("*******")
                        .WithTenantId("******")
                        .Build();

   
 

    var ewsScopes2 = new string[] { "https://graph.microsoft.com/.default" };
             
    var authResult2 = cca.AcquireTokenForClient(ewsScopes2).ExecuteAsync().Result;


// Configure the ExchangeService with the access token

    var _service = new ExchangeService();
                        _service.Url = new Uri("https://graph.microsoft.com/v1.0/me/calendar/events");

                   
                

_service.Credentials = new OAuthCredentials(authResult2.AccessToken);
               

 _service.ImpersonatedUserId = new ImpersonatedUserId(ConnectingIdType.SmtpAddress, "abc@mycompany.onmicrosoft.com");
            }
                   
    EmailAddressCollection roomList = _service.GetRoomLists();

While trying to access the GetRoomLists, we are getting the error “The request failed. The remote server returned an error: (400) Bad Request.”

AAD Configuration:
In Azure AD the Graph object has delegated permission to Calendars.Room resource.

 // Configure the ExchangeService with the access token
 var _service = new ExchangeService();
                    _service.Url = new 
Uri("https://graph.microsoft.com/v1.0/me/calendar/events");            
_service.Credentials = new OAuthCredentials(authResult2.AccessToken);
_service.ImpersonatedUserId = new ImpersonatedUserId(ConnectingIdType.SmtpAddress, "abc@mycompany.onmicrosoft.com");
        }
EmailAddressCollection roomList = _service.GetRoomLists();

This is all Exchange Web Services (EWS which is a SOAP based API) code so won't work against the Graph (which is REST based). The equivalent would be to use the Graph SDK https://learn.microsoft.com/en-us/graph/sdks/sdks-overview and the use the Places Endpoint. To use this endpoint you will need to the Place.Read.All Application permission.

https://learn.microsoft.com/en-us/graph/api/place-list?view=graph-rest-1.0&tabs=csharp

Note you might need to be aware of this issue with the v5 version of the SDK https://github.com/microsoftgraph/microsoft-graph-docs/issues/21503 as that will affect what your tying to do.