2D Jump Height Inconsistiency and Framerate Independence

I am relatively new to Unity, and I'm trying to build a 2D platformer. I have a working player controller, but I've noticed that the jump height is sometimes different between the game running in the editor and the actual build. I think this probably has to do with the fact that everything is happening in Update instead of FixedUpdate, and I feel like it might be related to framerate independence? I know that in order to get framerate independence I need to multiply something by Time.deltaTime, but every time I try this in this script, it makes the character unable to move/jump. I think I just need a little clarification on how FixedUpdate/Time.deltaTime work and thoughts on why this inconsistency might be happening.

Below is the working code. Thank you!!

 public float maxSpeed;               //currently set to 10
 public float jumpMax;                //currently set to 20  <- this is max velocity
 public float initialForce;           //currently set to 650
 public float acceleration;           //currently set to 100
 public LayerMask groundLayer;
 
 private bool grounded;
 private bool peaked;                 // true if the player has reached the max jump height
 private int jumped = 0;              // number of times jumped, for future use in double jumping
 private float lookDirection = 1;     // used in animation
     
 private Animator animator;
 private Rigidbody2D rigidbody;
     
 void Awake()
 {
             rigidbody = GetComponent<Rigidbody2D>();
             animator = GetComponent<Animator>();
 }
     
 void Update()
 {
             float move = Input.GetAxis("Horizontal");
             if (!Mathf.Approximately(move, 0.0f))
             {
                 lookDirection = move;
                 lookDirection = (lookDirection / Mathf.Abs(lookDirection));
             }
             animator.SetFloat("Look", lookDirection);
             animator.SetFloat("Speed", Mathf.Abs(rigidbody.velocity.x));
             rigidbody.velocity = new Vector2(move * maxSpeed, rigidbody.velocity.y);
        
       
             if (Input.GetButtonDown("Jump"))                //initializes the jump
             {
                 if (grounded)
                 {
                     rigidbody.AddForce(Vector2.up * initialForce);
                 }
             }
             if (Input.GetButton("Jump"))                    //allows variable jump heights
             {
                 if (rigidbody.velocity.y < jumpMax && !peaked)
                 {
                     if (rigidbody.velocity.y > 0.0001)      //prevents continuous jumping
                         rigidbody.AddForce(Vector2.up * acceleration);
                 }
                 if (rigidbody.velocity.y > jumpMax)
                 {
                     peaked = true;
                 }
             }
     
     
             if (rigidbody.velocity.y > 0.0001)
             {
                 animator.SetBool("Ascend", true);
                 animator.SetBool("Descend", false);
             }
             else if (rigidbody.velocity.y < -0.0001)
             {
                 animator.SetBool("Descend", true);
                 animator.SetBool("Ascend", false);
             }
             else
             {
                 animator.SetBool("Descend", false);
                 animator.SetBool("Ascend", false);
             }
 }
     
 void OnTriggerEnter2D(Collider2D other)
 {
             if (other.gameObject.tag == ("Ground"))
             {
                 jumped = 0;
                 grounded = true;
                 peaked = false;
                 animator.SetBool("Descend", false);
                 animator.SetBool("Ascend", false);
                 animator.SetTrigger("Grounded");
             }
 }
 void OnTriggerExit2D(Collider2D other)
 {
             if (other.gameObject.tag == ("Ground"))
             {
                 jumped = 1;
                 grounded = false;
             }
 }