How can I have spawned gameObjects be treated as individuals by other scripts?

Hi, I am spawning objects onto a conveyor belt by adding them to a list onCollision and removing them on exit, only as soon as one exits all clones are removed from the list and the conveyor belt ceases moving them. I've given each a unique name but I'm not sure if this can be utilised. I just want the conveyor belt to keep moving the objects. My code is below;

Conveyor Script

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 
 public class ConveyorBelt : MonoBehaviour
 {
 public float ConveyorSpeed;
 public Vector3 ConveyorDirection;
 public List<GameObject> onBelt;
 
 void Start()
 {
 }
 
 void Update()
 {
     for(int i = 0; i <= onBelt.Count -1; i++)
     {
         onBelt[i].GetComponent<Rigidbody>().velocity = ConveyorSpeed * ConveyorDirection * Time.deltaTime;
     }
 }
 
 private void OnCollisionEnter(Collision collision)
 {
     onBelt.Add(collision.gameObject);
 }
 private void OnCollisionExit(Collision collision)
 {
     onBelt.Remove(collision.gameObject);
 }
 }

Spawner Script

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 
 public class Spawner : MonoBehaviour
 {
 
     public Transform spawnPos;
     public GameObject spawnee;
     public int nextNameNumber;
 
 
     
     void Update() {
 
 
         if(Input.GetKeyDown("p")) {
              
 
           Instantiate(spawnee, spawnPos.position, spawnPos.rotation);
           spawnee.name = "enemy"+(nextNameNumber);
           nextNameNumber ++;
     }
 }
 }

Oh and the destroy script

 using System.Collections;
 
 using System.Collections.Generic;
 
 using UnityEngine;
 
 
 public class Destroyer : MonoBehaviour {
     
 
 public float lifeTime = 10f;
 
 void Update () {
     if(lifeTime > 0) {
         lifeTime -= Time.deltaTime;
         if(lifeTime <= 0) {
             Destruction();
     }
 }
     if(this.transform.position.y <= -20) {
         Destruction();
     }
 }
 
 void OnCollisionEnter(Collision coll) {
     if(coll.gameObject.name == "Destroyer") {
         Destruction();
     }
 }
 
 void Destruction() {
     Destroy(this.gameObject);
     }
 }

Many thanks for your time and assistance. Sorry that the code is scrappy, I'm using notepad. Regards Bodi.