There is an issue with type inference during serialization of an object.

[peijiehuang]

Source/destination types

using Newtonsoft.Json;

namespace ConsoleApp1
{
    internal class Program
    {
        private static JsonSerializerSettings SerializerSettings = new JsonSerializerSettings
        {
            TypeNameHandling = TypeNameHandling.All,
            ObjectCreationHandling = ObjectCreationHandling.Replace,
        };

        static void Main(string[] args)
        {
            var data = new Dictionary<string, object>
            {
                { "TEST", (Int16)123 },
                { "TEST2", (Int128)123 },
            };

            foreach (var item in data)
            {
                Console.WriteLine("data1:" + item.Value.GetType());
            }
            Console.WriteLine();
            Console.WriteLine();

            var jsonStr = JsonConvert.SerializeObject(data, SerializerSettings);

            Console.WriteLine(jsonStr);
            Console.WriteLine();
            Console.WriteLine();

            var data2 = JsonConvert.DeserializeObject<Dictionary<string, object>>(jsonStr, SerializerSettings);

            foreach (var item in data2)
            {
                Console.WriteLine("data2:" + item.Value.GetType());
            }

        }
    }
}

Source/destination JSON

{"$type":"System.Collections.Generic.Dictionary`2[[System.String, System.Private.CoreLib],[System.Object, System.Private.CoreLib]], System.Private.CoreLib","TEST":123,"TEST2":"123"}

Expected behavior

The data should retain the data type of TEST as int16 and TEST2 as int128.

Actual behavior

The data was actually converted to retain the data type of TEST as int32 and TEST2 as string.

Steps to reproduce

The complete code is provided above, and here are the images.