Question Jumps to high

Hello, I'm making a 2.5D platformer and I was trying to make my character jump and it does not work, I mean it was working but when I press "space" it jumped way to high.

Code (CSharp):

1.  
2.     public float movementSpeed = 250;
3.     public float fallMultiplayer = 2.5f;
4.     public float lowJumpMultiplayer = 2f;
5.     public float jumpForce = 5;
6.  
7.     private Rigidbody rb;
8.  
9.     private void Awake()
10.     {
11.         rb = GetComponent<Rigidbody>();
12.     }
13.  
14.     void FixedUpdate()
15.     {
16.         // Player movement
17.         float xMovement = Input.GetAxisRaw("Horizontal");
18.         rb.velocity = new Vector3(xMovement, rb.velocity.y, 0f) * movementSpeed * Time.deltaTime;
19.         // Player Jump
20.         if (Input.GetButtonDown("Jump"))
21.         {
22.             rb.velocity = Vector3.up * jumpForce * Time.deltaTime;
23.         }
24.         if (rb.velocity.y < 0)// improves jump(makes jump similar to mario jump)
25.         {
26.             rb.velocity += Vector3.up * Physics.gravity.y * (fallMultiplayer - 1);
27.         }
28.         else if (rb.velocity.y > 0 && !Input.GetButton("Jump"))
29.         {
30.             rb.velocity += Vector3.up * Physics.gravity.y * (lowJumpMultiplayer - 1);
31.         }
32.  
33.     }

 

The jump now work just that I have to set I've to set it very high like to 100
Here's a clip of what happens: