Casting broke my jumping

[hushed wedge]

using System.Collections;
using UnityEngine;
 
 
public class ShieldController : MonoBehaviour
{
    public Transform ShieldTform;
    public Transform PlayerTform;
    public Rigidbody2D rb2D;
    public float JumpSpeed;
    public float fallMultiplier;
    public float lowJumpMultiplier;
    public bool canJump;
    public bool isJump;

    void Update() {

        //Jump button check
        if (Input.GetKeyDown("space")) {
            isJump = true;
        }

        if (Input.GetKeyUp("space")) {
            isJump = false;
        }

        //Rotate to point at cursor
        Vector3 mousePosition = Input.mousePosition;
        mousePosition = Camera.main.ScreenToWorldPoint(mousePosition);
 
        Vector2 direction = new Vector2(
            mousePosition.x - transform.position.x,
            mousePosition.y - transform.position.y
        );
 
        transform.up = direction;

        //Better fall
        if (rb2D.velocity.y < 0) {
            rb2D.velocity += Vector2.up * Physics2D.gravity.y * (fallMultiplier - 1) * Time.deltaTime;
        } else if (rb2D.velocity.y > 0 && !Input.GetButton("Jump")) {
            rb2D.velocity += Vector2.up * Physics2D.gravity.y * (lowJumpMultiplier - 1) * Time.deltaTime;
        }
    }


    void FixedUpdate() {
        //Jump
        if (isJump == true) {
            if (canJump == true) {
                Debug.Log("Jump");
                rb2D.velocity += (new Vector2(ShieldTform.position.x, ShieldTform.position.y) - new Vector2(PlayerTform.position.x, PlayerTform.position.y)).normalized * JumpSpeed;
            }
        }
    }

    //Jump collision check
     void OnTriggerEnter2D(Collider2D other) {
        if (other.CompareTag("Level")) {
            canJump = true;
        }
    }

    void OnTriggerExit2D(Collider2D other) {
        if (other.CompareTag("Level")) {
            canJump = false;
        }
    }
}

okay, Ive got this player and a sheild that rotates around it, and when I jump I want to add a force in the opposite direction of the shield relative to the player.
had some problems getting casting to work (new to this) no errors anymore, but when I press jump it wont add any force. what am I doing wrong?
and more importantly, how can I fix it?