How do I make Destroy(gameObject) work in my script?

My code is a little long for me to post the entirety of it, but I was able to recreate the issue I'm having with a much trimmed down script, which is shown below. I'm not including what I did to create the mesh since I feel it is irrelevant to my question, and because the script is trimmed down from my original code, it might seem overly complicated for what I'm trying to do. However, the problem still remains so please bear with me.

 using UnityEngine;
 using System.Collections;
 
 public class CoreController : MonoBehaviour {
 
    private RaycastHit2D[] leftHits;
    private bool moveLeft;
 
    public void createMesh() {
       //create mesh
    }
 
    void Start () {
       moveLeft = false;
       tag = "step1";
       createMesh();
    }
     
    void Update () {
       leftHits = Physics2D.RaycastAll(new Vector2(transform.position.x-0.1f, transform.position.y+1.5f/2), -Vector2.right);
         
       if(Input.GetKeyDown("left")) {
          moveLeft = true;
          tag = "step2";
       }
 
       if(!GameObject.Find("step1")) {
          if(moveLeft) {
             if(leftHits.Length > 0) {
                if(tag == "step2" && leftHits[0].collider.gameObject.tag == "step2") {
                   Destroy(gameObject);
                }
             }
          }
  
          //Part A
          if(tag == "step2") {
             tag = "step3";
          }
       }
    }
 }

This script is attached to a gameObject that is instantiated by another script to many random locations on the x-y plane. Without Part A, if a gameObject detects another gameObject to the left of it with the same tag "step2", the gameObject gets successfully destroyed when I click the left button. Now, I want the remaining gameObjects to have the tag "step3". However, with Part A included, the Destroy(gameObject) line is skipped and every gameObject remains and attains the new tag "step3".

It seems that when I include Part A, the if condition

 (tag == "step2" && leftHits[0].collider.gameObject.tag == "step2")

is never true for any of instantiated gameObjects because Part A gets executed first. But why?

Any help would be much appreciated.

Note: I tried FatWednesday's suggestion of putting "return;" right after the Destroy(gameObject) line, but I'm still getting the same problem.