How to differentiate objects with the same script?

I posted another question but I didnt really know what the issue was but I found a more detailed answer so I know what I need to fix but im not sure how to.

So basically, I have multiple tree objects, all with the same script that add one to a variable called woodAmount when you click, but when I click on one of the objects because the condition has been set to true the script runs on all the trees that have the script so how can I differentiate them so that they only run when they are clicked. I was hoping I wouldnt have to use tags or smth like that so what is the simplest but effective way to fix this issue?

Here is the script attached to the trees :

 void Update()
     {
         if (Input.GetMouseButtonDown(0))
         {
             RaycastHit2D rayHit = Physics2D.Raycast(Camera.main.ScreenToWorldPoint(Input.mousePosition), Vector2.zero);
             
             if (rayHit.collider != null)
             {
                 Debug.Log("Target Position: " + rayHit.collider.gameObject.transform.position);
                 GameObject.Find("GameManager").GetComponent<GameManagerGen>().TreeHit();
             }
         }
     }