Why does my character sometimes jump higher than other times?

When I use this code to let my character jump, it sometimes jump higher than other times. I am making a 2D platformer
using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class PlayerMovement : MonoBehaviour
{

private float Speed = 15f;
private float JumpForce = 15000f;

public Rigidbody rb;

public Transform groundedEnd;

void Start()
{
    rb = GetComponent<Rigidbody>();
}

void Update()
{
    Move();
    Raycasting();
}

void FixedUpdate()
{
    JumpKey();
}

void Move()
{
    float Move = Input.GetAxis("Horizontal") * Speed;
    Move *= Time.deltaTime;
    transform.Translate(Move, 0, 0);
}

void JumpKey()
{
    float JumpHeight = Input.GetAxisRaw("Jump") * JumpForce;
    if (Input.GetKeyDown("space"))
    {
        rb.AddForce(transform.up * JumpHeight * Time.deltaTime);
        
    }
}

void Raycasting()
{
    Debug.DrawLine(this.transform.position, groundedEnd.position, Color.green);
}

}

Try to change Time.deltaTime to Time.fixedDeltaTime in your rb.AddForce. It may be that the value irregularly oscillates depending on your frame rate which causes fluctuations in actual jump force.