How to make single score affected by multiple collision objects?

I am trying to make a simple pachinko game. What should happen is, a ball spawns, the count decreases by 1, and if the ball lands in a basket, the count goes back up. I am able to make the score decrease and increase. But these scores seem to be individual from each other.

For example: I start at 100 balls. I spawn one ball and now have 99 remaining. The ball lands in the basket and I'm back to 100. However, the next time I spawn a ball I now have 98 instead of 99. It's as if the decreasing and increasing of the score are out of sync.

How would I go about fixing this? Here's my code: public class GameManager : MonoBehaviour { public GameObject ballPrefab;

 public Text CounterText;

 public static int Count = 100;

 // Start is called before the first frame update
 void Start()
 {
     Count = 100;
     
 }

 // Update is called once per frame
 void Update()
 {
     if (Input.GetKeyDown("space"))
     {
         Instantiate(ballPrefab);
     }
 
 }

 public void OnCollisionEnter(Collision other)
 {
     if (other.gameObject.tag == "LoseBall")
     {
         GameManager.Count -= 1;
     }

     if (other.gameObject.tag == "Gain1Ball")
     {
         GameManager.Count += 1;
     }
 }

}