How serialization and deserialization happens in API here

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Microservices

I have this code below which calls a MicroService called "RydoService" which returns a HttpResponse containing the data stored in "response".

First Question : Is the content in the response serialized ?

If yes, then why do we need to use ReadAsByteArrayAsync() on the response content ?
and then later we are deserialising the content. That I get it.

My Question is that Isnt RydoService already sent the serialised content here over the network ?

public async Task<(bool IsSuccess, IEnumerable<Order> Orders, string ErrorMessage)> GetOrdersAsync(int customerId)
      {
          try
          {
              var client = httpClientFactory.CreateClient("RydoOrderService");
              var response = await client.GetAsync($"api/orders/{customerId}");
              if(response.IsSuccessStatusCode)
              {
                  var content = await response.Content.ReadAsByteArrayAsync();
                  var options = new JsonSerializerOptions() { PropertyNameCaseInsensitive = true };
                  var result = JsonSerializer.Deserialize<IEnumerable<Order>>(content, options);
                  return (true, result, null);
              }

              return (false, null, response.ReasonPhrase);
          }
          catch(Exception ex)
          {
              logger?.LogInformation(ex.ToString());
              return (false, null, ex.Message);
          }
      }

What I have tried:

Googling. No Luck. So Help :)
Waiting..........................................