Instantiated prefab object following Player if SpriteRenderer's alpha is modified

So i'm making a simple pixel art 2d platformer. During a certain player action i want to create a trail of circles after him. I have a prefab object for this, which contains a SpriteRenderer, and a Script.

The problem is that all of the instantiated prefabs follow the player transform like if they were child objects (they're not). The weird thing is that if i comment out the line that modifies the Flash prefabs SpriteRenderer alpha value,

"sr.color = new Color(sr.color.r,sr.color.b,sr.color.g, sr.color.a * (factor * Random.Range(0.25f,0.75f)));"

it does make a trail like i want, and every clone object stays at the position it was instantiated...

This is the relevant code:

Code (CSharp):

1. public class Flash : MonoBehaviour
2. {
3.     public SpriteRenderer sr;
4.     private float duration;
5.     private float factor;
6.     private float startTime;
7.  
8.     private void Start()
9.     {
10.         transform.parent = null;
11.         transform.Translate(Random.insideUnitCircle * 0.325f);
12.         startTime = Time.time;
13.         duration = Random.Range(1f,3f);
14.     }
15.  
16.     private void Update()
17.     {
18.         factor = Mathf.Max(0f, 1 - ((Time.time - startTime) / duration));
19.         sr.color = new Color(sr.color.r,sr.color.b,sr.color.g, sr.color.a * (factor * Random.Range(0.25f,0.75f)));
20.  
21.         if (Time.time - startTime > duration) {
22.             Destroy(gameObject);
23.         }
24.     }
25. }

The SpriteRenderer sr is set to be the prefabs own SpriteRenderer in the editor. The prefab is instantiated in the following code in the PlayerController script:

Code (CSharp):

1.     protected void FlashTrail(Vector2 flashPos)
2.     {
3.         if (Time.time - lastFlash > flashRate){
4.             Instantiate(flashPrefab, new Vector3(flashPos.x, flashPos.y, 0f), Quaternion.identity);
5.             lastFlash = Time.time;
6.         }
7.     }

Code (CSharp):

1. protected void Update()
2.     {      
3.         if (isAttacking){
4.             FlashTrail(new Vector2(transform.position.x, transform.position.y));
5.             if ((Time.time - lastAttack > attackDuration) || (Vector2.Distance(transform.position, attackTarget) < 0.25f)) {
6.                 isAttacking = false;
7.             }
8.         }
9.     }

I'm fairly new to Unity and i really have no clue Anyone that can point me in the right direction?

Thanks a lot!