问我的倒计时计时器卡住了，游戏无法停止

EN

//if game is continued, close deathUI and start timer
public void continueGame()
{
    // Add this line to prevent accident like double click... which will start multiple coroutine and cause unexpected result
    if (CountDown) return;
    CountDown = true;
    deathMenuUI.SetActive(false);
    // Since you want your game to still being paused for 3 seconds before resuming
    Time.timeScale = 0;
    StartCoroutine(LoseTime());
}

private void AfterCountdownFinished()
{
    // important. You must set your Time.timeScale back to its default value
    // because even if you reload your scene the timeScale remain the same which can cause you to encounter freeze error which you might spend time to search for the problem

    Time.timeScale = 1;
    GameOver = CountDown = false;
    countDownUI.SetActive(false);
    // You want to write your restart/continue logic here
    // Example:
    // reload the level
    // SceneManager.LoadScene(SceneManager.GetActiveScene().buildIndex);
}

IEnumerator LoseTime()
{
    // I forgot this part (which you pointed out)
    countDownUI.SetActive(true);
    // Here is how you can improve performance

    // It seems you can't create and reuse it like WaitForSeconds
    // var delay = new WaitForSecondsRealtime(1);
    // Set this the text here so it will display (3 in your case) for 1 second before start decreasing
    countDownText.text = timeLeft.ToString();

    // If your level will restart after the countdown ends then you don't need to create another variable like below. You can just use timeLeft directly
    int time = timeLeft;
    while (time > 0)
    {
        // Edited here
        yield return new WaitForSecondsRealtime(1);
        time--;
        // Here you don't set your UI text every frame in the update but you only set it only when there is change on timeLeft
        countDownText.text = time.ToString();
    }
    // When countdown ended. You don't need to call StopCoroutine
    AfterCountdownFinished();
}