How do I stop my code from saying "You win" if you respawn

So this is a logic error I think. So the player is not allowed to jump from the top of the building straight to the floor. If the player manages to jump to the other building then to the floor, the text will display “You win!”. The code works but when the player reaches the bottom, for a brief moment you can see the text display “You win!”. I tried using if isTrue = 1 then respawn and say “You lost” but that hasn’t worked so far. I am not sure what I am missing from the logic.

     using System.Collections;
     using System.Collections.Generic;
   using UnityEngine.UI; 
  using UnityEngine;
     using UnityEngine.SceneManagement;

    public class Countdown : MonoBehaviour
 {
         float currentTime = 0f;
           float startingTime = 15f;
        public float maxHeight = 13;
       public Transform Player;
       public int isTrue = 1;

[SerializeField] Text countdownText;

void Start()
{
    currentTime = startingTime;
}

void Update()
{

    currentTime -= 1 * Time.deltaTime;
    countdownText.text = currentTime.ToString("Time left: ") + currentTime.ToString("0");
    if (currentTime <= 0 && countdownText.text != "You won!" && isTrue == 1)
    {
        countdownText.text = currentTime.ToString("You lost!");
        Respawn();

    }

    if(Player.position.y <= 1.3 && currentTime > 0 && isTrue == 0)
    {
        
        countdownText.text = currentTime.ToString("You won!");
    }

}

void OnCollisionEnter(Collision collision)
{

    float impactVelocity = Mathf.Abs(collision.relativeVelocity.y);

    float height = impactVelocity * impactVelocity / (2 * Mathf.Abs(Physics.gravity.y));
    if (height > maxHeight)
    {
        
        Respawn();
    }
    else if(height <= maxHeight)
    {
       isTrue = 0;
    }
}
void Respawn()
{
    SceneManager.LoadScene("FirstScene");

}

}

Any reason not to just check the victory condition and change the text to “You Won” in your OnCollisionEnter function? So you can still have the time check for failure in Update, but the height check would probably live easier in the collision function. Unless of course there’s another reason to put it in Update. Hope that helps!