Problem between my player jump and player movement

i made a simple jump and movement, but i have a problem. If i comment the 75 line (in FixedUpdate) of my code "rb2d.MovePosition(rb2d.position + mov speed Time.deltaTime);" my jump work fine, but if i not coment this line, the jump not work and the player gravity is like too less, but not change in the inspector, i'm confussed, i'm a bit noob and i dont what happends. Thanks!

 public class PlayerMovement : MonoBehaviour
 {
     [Header("Movement")]
     [SerializeField] float speed = 4f;
     [SerializeField] bool canMove;
     CircleCollider2D feetColl;
 
     private Vector2 mov = new Vector2(1, 1);
 
     Animator anim;
     Rigidbody2D rb2d;
 
     [Header("Jump")]
     [Range(1,10)]
     [SerializeField] float jumpVelocity = 1f;
     public bool jumpRequest;
 
     public float fallMultiplier = 2.5f;
     public float lowJumpMultiplier = 2f;
     
 
     void Awake()
     {
         rb2d = GetComponent<Rigidbody2D>();
     }
 
     void Start()
     {
         anim = GetComponent<Animator>();
         rb2d = GetComponent<Rigidbody2D>();
         feetColl = GetComponent<CircleCollider2D>();
         canMove = true;
     }
 
     void Update()
     {
         if (canMove)
         {           
           //  Falling();
             JumpRequest();
         }
     }
     /*
     private void Falling()
     {
         if (!feetColl.IsTouchingLayers(LayerMask.GetMask("ground")))
         {
             anim.SetBool("falling", false);
         }
         else
         {
             anim.SetBool("falling", true);
         }
     }
     */
 
     private void Run()
     {
         mov = new Vector2(Input.GetAxisRaw("Horizontal"), 0f);
 
         if (mov != Vector2.zero)
         {
             anim.SetFloat("movX", mov.x);
             anim.SetBool("running", true);
         }
         else
         {
             anim.SetBool("running", false);
         }
     }
 
     void FixedUpdate()
     {
         //Movement
         rb2d.MovePosition(rb2d.position + mov * speed * Time.deltaTime);
         Run();
         Jump();
     }
     
     private void JumpRequest()
     {
         if (Input.GetButtonDown("space"))
         {
             jumpRequest = true;
         }
     }
     
     private void Jump()
     {
         
         if (jumpRequest && !feetColl.IsTouchingLayers(LayerMask.GetMask("ground")))
         {
             return;
         }
         if (jumpRequest)
         {
             rb2d.AddForce(Vector2.up * jumpVelocity, ForceMode2D.Impulse);            
             anim.SetTrigger("jump");
             Debug.Log("jump");
             jumpRequest = false;
         }
 
         if (rb2d.velocity.y < 0)
         {
             rb2d.gravityScale = fallMultiplier;
         }
         else if (rb2d.velocity.y > 0 && !Input.GetButton("space"))
         {
             rb2d.gravityScale = lowJumpMultiplier;
         }
         else
         {
             rb2d.gravityScale = 1f;
         }
     }
     
 }