When creating C# generic classes with static functions should the return type concreate class types?

public class MyClass<TKey, TValue> : IBase
{
    TValue v;
    public Dictionary<TKey, TValue> myData = new Dictionary<TKey, TValue>();

    public Dictionary<TKey, TValue> GetData() { return myData; }

    public static MyClass<string, MyData> CreateMyData()
    {
        MyClass<string, MyData> tmp = new MyClass<string, MyData>();
        return tmp;
    }
}

public class MyClass<TKey, TValue> : IBase
{
    TValue v;
    public Dictionary<TKey, TValue> myData = new Dictionary<TKey, TValue>();

    public Dictionary<TKey, TValue> GetData() { return myData; }

    public static MyClass<string, MyData> CreateMyData()
    {
        MyClass<string, MyData> tmp = new MyClass<string, MyData>();
        return tmp;
    }
}

public static MyClass<string, MyData> Deserialize(string filename)
{
    string jsonString = File.ReadAllText(filename);
    MyCall<string, MyData> tmp = JsonSerializer.Deserialize<MyClass<string, MyData>>(jsonStrin);
    return tmp;
}

public static MyClass<string, MyData> Deserialize(string filename)
{
    string jsonString = File.ReadAllText(filename);
    MyCall<string, MyData> tmp = JsonSerializer.Deserialize<MyClass<string, MyData>>(jsonStrin);
    return tmp;
}