以下代码段是否可以由于使用lock_guard已采用的互斥锁而导致未污染的行为？如果在同一代码段中使用unique_lock代替lock_guard是否安全？我知道有std::unique_lock<T>::lock/unlock()

#include <iostream>
#include <thread>
#include <mutex>
#include <chrono>

std::mutex m1;
void func(int count ){

    std::lock_guard lG{m1};
    std::cout << std::this_thread::get_id() << std::endl;
    if(count == 1) {
        m1.unlock();
        std::this_thread::sleep_for(std::chrono::duration<size_t,std::ratio<1,1>>{6});
        m1.lock();
    }
    std::cout << std::this_thread::get_id() << std::endl;
}
int main()
{
    std::thread t1 {func,1};
    std::thread t2 {func,9};
    t1.join();
    t2.join();
}