(2D) What is wrong with my code that is preventing me from crouching ? - PlayerMovement Script 2D

For some reason, even though I have implemented the crouching mechanic into this code, nothing is happening in the actually game. Can anyone help? I'm new to coding.

    using System.Collections;
    using System.Collections.Generic;
    using UnityEngine;

    public class PlayerMovement : MonoBehaviour
    {

    public CharacterController2D controller;

    public float runSpeed = 40f;

    float horizontalMove = 0f;
    bool jump = false;
    bool crouch = false;

    // Update is called once per frame
    void Update()
    {
        horizontalMove = Input.GetAxisRaw("Horizontal") * runSpeed;

        if (Input.GetButtonDown("Jump"))
        {
            jump = true;
        }

        if (Input.GetButtonDown("Crouch"))
        {
            crouch = true;
        } else if (Input.GetButtonUp("Crouch"))
        {
            crouch = false;
        }
    }

    void FixedUpdate()
    {
        //Move our character
        controller.Move(horizontalMove * Time.fixedDeltaTime, crouch, jump);
        jump = false;
    }
}

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