Question 2D animation no longer working - Need Help

I am updating a 2D game that I wrote in 2017. I noticed that when I upgraded to the 2021 version my animations go super fast. Can you tell what I need to do to upgrade my 2D C# animation script. Thank you so much!

Code (CSharp):

1. using UnityEngine;
2. using UnityEngine.UI;
3. using System.Collections;
4.  
5.  
6. public class CloudAnime : MonoBehaviour {
7.  
8.     public Image imgCloud;
9.     public Image imgStart;
10.     public Image imgEnd;
11.  
12.     public float cloudspeed = 3;
13.  
14.     private float sw;
15.  
16.     void Start () {
17.         sw = Screen.width;
18.         Debug.Log (sw);
19.     }
20.  
21.     // Update is called once per frame
22.     void Update () {
23.  
24.     //    RectTransform rt = imgCloud.rectTransform;
25.     //    imgCloudWidth = rt.rect.width;
26.  
27.         Vector3 pos = imgCloud.transform.position;
28.         Vector3 startPos = imgStart.transform.position;
29.         Vector3 endPos = imgEnd.transform.position;
30.  
31.         if (pos.x < endPos.x) {      
32.             Vector3 setThis = new Vector3 (startPos.x, imgCloud.transform.position.y);  
33.             imgCloud.transform.position = setThis;
34.         }
35.             else
36.         {
37.             pos.x -= cloudspeed;
38.             imgCloud.transform.position = pos;
39.         }
40.  
41.     }
42. }
43.