2d Top Down Shooter Jerky Movement

Hey guys I am a newbie in unity. Currently I am making a 2d top down shooter based game. And here comes the bug. So character movements I am using Brackeys top down shooting tutorial. And here is the code.

using System.Collections;
using System.Collections.Generic; using UnityEngine; public class PlayerMovement :MonoBehaviour

{

 [SerializeField]private float movementSpeed = 5f;

  [SerializeField]private Camera cam;

   private Rigidbody2D playerRb;

   private Vector2 movmentVector;

   private Vector2 mosusePos;

   private Vector2 lookDirectionVec;

 
  //Start Called once
  private void Start()
  {
      playerRb = gameObject.GetComponent<RigidBody2D>();
 
  }
 
  //Update Called Every Frame
     private void Update()
   {
       GetingInput();
      MouseRotation();
  }
 
  //Fixed Update 
  private void FixedUpdate()
  {
      playerRb.MovePosition(playerRb.position
          + movmentVector * Time.fixedDeltaTime);
      // playerRb.velocity = new Vector2(movmentVector.x, movmentVector.y);
  }
 
  private void GetingInput()
  {
      Vector2 inputVector = new Vector2(Input.GetAxisRaw("Horizontal"),Input.GetAxisRaw("Vertical"));
      movmentVector = inputVector.normalized *movementSpeed;
 
      lookDirectionVec = cam.ScreenToWorldPoint(Input.mousePosition) - transform.position;
  }
  private void MouseRotation()
  {
      float angleToRotate  = Mathf.Atan2(lookDirectionVec.y,lookDirectionVec.x) * Mathf.Rad2Deg - 90f;
      Quaternion qRotation = Quaternion.AngleAxis(angleToRotate,Vector3.forward);
      transform.rotation = qRotation;
  } 

}

But whenever I test the game the movements are jittering. Like the shutter the movement. I found some solutions on web articles and unity forms. The first I tried is to change RigidBody2d.MovePositions() to RigidBody2d.Velocity but the result is also the same and the second one is to change the camera size 5 to 10. Second one is kind of a work but it stills jittering. So any solutions to this. Here are the camera properties and player properties.