Advanced Jump

[lavish elm]

Hello, I am trying to make a controllable jump for a metroidvania. When I run the code, the player doesn't stop jumping when the timer runs out for the player.
The code is in the next message.

using UnityEngine;

public class PlayerJump : MonoBehaviour
{

[Header("Jump Ray Cast Settings/Jump Settings")]
public Vector2 boxSize;
public float boxDistance;
public LayerMask layerMask;
bool canJump;
public float maxJumpTimer;
float jumpTimer;
float gravity;
public float gravityMultiplier;
public float jumpSpeed;
bool jumping;
[Header("Ground Raycasts")]
public Vector2 groundSize;
public float groundDistance;

there's the variables

public bool IsGrounded()
{
if (Physics2D.BoxCast(transform.position, boxSize, 0, -transform.up, boxDistance, layerMask))
{
return true;
}
else
{
return false;
}
}
public bool TouchingGround()
{
if (Physics2D.BoxCast(transform.position, groundSize, 0, -transform.up, groundDistance, layerMask))
{
return true;
}
else
{
return false;
}
}
public void OnDrawGizmos()
{
Gizmos.DrawWireCube(transform.position - transform.up * boxDistance, boxSize);

    Gizmos.DrawWireCube(transform.position - transform.up * groundDistance, groundSize);
}
// Start is called once before the first execution of Update after the MonoBehaviour is created
void Start()
{
    jumpSpeed *= Time.deltaTime;
}

// Update is called once per frame
void Update()
{
    if (IsGrounded())
    {
        jumpTimer = maxJumpTimer;
    }
    else
    {
        gravity -= 0.1f * Time.deltaTime * gravityMultiplier;
    }

    if (jumpSpeed > 0) canJump = true;
    else if (jumpSpeed <= 0) canJump = false;

    if (Input.GetKey(KeyCode.Space))
    {
        jumping = true;
    }

    else
    {
        jumping = false;
    }

    if (canJump)
    {
        if (jumping)
        {
            gravity = jumpSpeed;
            jumpTimer -= 1 * Time.deltaTime;
        }
    }
    
    if (TouchingGround())
    {
        if (!Input.GetKey(KeyCode.Space))
        {
            gravity = 0;
        }
    }
}
void LateUpdate()
{
    transform.position -= Vector3.down * gravity;
}

}

There's the rest