Example of HealthCollectable prefab script for respawning itself

HealthCollectable.cs

using System.Collections;
using UnityEngine;

public class HealthCollectable : MonoBehaviour
{
    public float health = 20.0f;
    public float rotationSpeed = 25.0f;
    public float cooldown = 1.0f;
    private bool wasUsed = false;
    public GameObject healthPrefab;
    private GameObject player;

    private void Start()
    {
        player = GameObject.FindGameObjectWithTag("Player");
        healthPrefab = gameObject;
    }

    // Update is called once per frame
    void Update()
    {
        transform.Rotate(Vector3.up * Time.deltaTime * rotationSpeed);
    }

    private void OnTriggerEnter(Collider other)
    {
        PlayerManager pManager = player.GetComponent<PlayerManager>();
        if (other.gameObject.CompareTag("Player") && pManager.health < 100)
        {
            pManager.Heal(health);
            healthPrefab.SetActive(false);
            wasUsed = true;
        }
    }

    IEnumerator GenerateNewHealthPrefab()
    {
        Debug.Log("Coroutine!!");
        if (wasUsed)
        {
            Debug.Log("About to wait!!");

            yield return new WaitForSeconds(cooldown);
            
            healthPrefab.SetActive(true);
 
            wasUsed = false;
        }
    }

    private void FixedUpdate()
    {
        StartCoroutine(GenerateNewHealthPrefab());
    }
}

Screenshot of unity configuration for the script on the prefab: