Player Stopping Suddenly?

I have been trying hard to fix this, but I cant figure out any solution.
This is in in the editor:

This is in the build in mobile phone:

As you can see the sphere is stopping minutely after a certain amount of time in the build. These are the Scripts:

This is the movement Script:

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 
 public class Movement : MonoBehaviour
 {
     public GameObject gun;
     public int speed = 10;
 
     public Rigidbody rb;
 
     float h;
     float v;
     
 
     public Joystick joystick;
 
     // Update is called once per frame
     void FixedUpdate()
     {
         h = joystick.Horizontal;
         v = joystick.Vertical;
         GetComponent<Rigidbody>().AddForce(Vector3.forward * speed * v);
         GetComponent<Rigidbody>().AddForce(Vector3.right * speed * h);
         rb.velocity = rb.velocity * (1 - Time.deltaTime * rb.drag);
 
     }
 
     private void Update()
     {
 
         gun.transform.position = transform.position;
     }
 }

This is the gun script:

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 
 public class Gun : MonoBehaviour
 {
     public Joystick joystick;
 
     float yaw;
     public float LerpSpeed;
     private float finalYaw;
     public float turnSpeed;
     // Start is called before the first frame update
     void Start()
     {
         
     }
 
     // Update is called once per frame
     void FixedUpdate()
     {
         finalYaw = Mathf.Lerp(finalYaw, yaw, Time.deltaTime * LerpSpeed);
 
         yaw += joystick.Horizontal * turnSpeed;
         transform.eulerAngles = new Vector3(transform.rotation.x, -finalYaw, transform.rotation.y);
     }
 }

This is the Camera Script(I copied it from the internet):

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 
 public class CameraMovement : MonoBehaviour
 {
     public GameObject player;        //Public variable to store a reference to the player game object
 
 
     private Vector3 offset;            //Private variable to store the offset distance between the player and camera
 
     // Use this for initialization
     void Start()
     {
         //Calculate and store the offset value by getting the distance between the player's position and camera's position.
         offset = transform.position - player.transform.position;
     }
 
     // LateUpdate is called after Update each frame
     void LateUpdate()
     {
         // Set the position of the camera's transform to be the same as the player's, but offset by the calculated offset distance.
         transform.position = player.transform.position + offset;
     }
 }

This is My Hierarchy:

As you can guess the parent "Player" is not moving. The sphere is moving and the gun is simply following the position of the sphere.

I don't understand why the sphere is stopping minutely after a certain amount of time. The sphere is not stopping because of sphere is colliding with the gun. The gun is at a considerable distance form the sphere. Can Some one please help me.