wstring decreasing by one character every time it is printed c++

Question

Hello and today I came across something very interesting. Every time I send my wstring through anything it decreases the amount of characters by one. I am new to c++ and dont really understand what I am doing.

#include <windows.h>
#include <iostream>
#include <conio.h>
#include <thread>
#include <WinUser.h>
#include <string>
#include <vector>

using namespace std;

int nameingNumber = 1;

void test()
{

while (true)
{
    
    std::wstring msg = L"BotUser" + nameingNumber;        
    wcout << msg << "\n";
    Sleep(500);
    nameingNumber++;
}

}

Output

 otUser
 tUser
 User
 ser
 er
 r