Unity Question: How to make all positions (with array) initialized? - unity3d

Question

I'm the beginner of game coding, and meet some problem...
I would like to make coin stack and then click the coin all the coin would become small and fly to dedicate position, however, the coin position wasn't initialized which causes the Vector3 of coin move up 0.1f every time...
Please help me to solve it!
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.Networking;
public class createcoin : MonoBehaviour
{ public Transform RightCoinArea;
public Transform LeftCoinArea;
public Sprite sprite1;
List<Vector3> rightcoinpos = new List<Vector3>();
List<Vector3> leftcoinpos = new List<Vector3>();
public Vector3 [] rightpos= new Vector3 [6] ;
public Vector3[] leftpos = new Vector3[6];
// Start is called before the first frame update
void Start()
{
rightcoinpos.Add(rightpos);
leftcoinpos.Add(leftpos);
}
//create coin
public async void coincreate()
{
//coin stack random
for (float i = 0; i <= 0.1f; i += 0.1f)
{
var coin8 = await PoolSystem.Instance.GetGameObject(eBundle.Game, "Flycoin",
rightcoinpos[Random.Range(0, rightcoinpos.Count)] += Vector3.up * i, new Vector3(0.4f, 0.4f, 04f), sFileExtension.Prefab, RightCoinArea);
//to initialize sprite
coin8.GetComponent<SpriteRenderer>().sprite = sprite1;
}
//coin stack random
for (float i = 0; i < 0.2f; i += 0.1f)
{
var coin9 = await PoolSystem.Instance.GetGameObject(eBundle.Game, "Flycoin", leftcoinpos[Random.Range(0, leftcoinpos.Count)] += Vector3.up * i, new Vector3(0.4f, 0.4f, 04f), sFileExtension.Prefab, LeftCoinArea);
//to initialize sprite
coin9.GetComponent<SpriteRenderer>().sprite = sprite1;
}
}
public void Moveout()
{
//gameobject back to the objectpool
if (RightCoinArea.gameObject.transform.localScale == new Vector3(0, 0, 0))
{
PoolSystem.Instance.Recover(RightCoinArea.gameObject);
}
if (LeftCoinArea.gameObject.transform.localScale == new Vector3(0, 0, 0))
{
PoolSystem.Instance.Recover(LeftCoinArea.gameObject);
}
//delete all the position in List
rightcoinpos.Clear();
leftcoinpos.Clear();
//to initialize the position
Vector3 tempos_R = rightpos;
Vector3 tempos_L = leftpos;
rightcoinpos.Add(rightpos);
leftcoinpos.Add(leftpos);
}
public void click()
{
coin_test.GetComponent<SpriteRenderer>().sprite = sprite2_test;
//coin fly to end dedicate pos
DOTween.To(setter: value =>
{
coin_test.position = Parabola(start_test.position, new Vector3(0, 4.5f, 0), 1.5f, value);
}, startValue: 0, endValue: 1, duration: 1.5f)
.SetEase(Ease.Linear);
//change coin scale
transform.DOScale(0.0f, 2.0f).OnComplete(Moveout);
}
//Parabola
public static Vector3 Parabola(Vector3 start, Vector3 end, float height, float t)
{
float Func(float x) => 0.5f * (-height * x * x + height * x);
var mid = Vector3.Lerp(start, end, t);
return new Vector3(mid.x, Func(t) + Mathf.Lerp(start.y, end.y, t), mid.z);
}
}