jump issue

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

public class PlayerControls : MonoBehaviour
{
    // Components

    [Header("Movement Variables")]
    [SerializeField] private float movementSpeed = 36.8f;
    [SerializeField] private float maxMovementSpeed = 14f;
    [SerializeField] private float linearDrag = 8.9f;
    private float baseMovementSpeed;
    private float baseMaxMovementSpeed;

    public float sprintMultiplier = 1.5f;
    private bool isSprinting => Input.GetKeyDown(KeyCode.LeftShift);

    [Header("Jump Variables")]
    [SerializeField] private float jumpForce = 11f;
    [SerializeField] private float aerialLinearDrag = 2.5f;
    [SerializeField] private float fallMultiplier = 8f;
    [SerializeField] private float lowFallMultiplier = 5f;
    private bool canJump => Input.GetButtonDown("Jump") && isGrounded;



    // Gravity Components
    [Header("Ground Collision Variables")]
    [SerializeField] private LayerMask groundLayer;
    [SerializeField] private float groundRaycastLength;
    private bool isGrounded;



    // Player RigidBodyControls

    private Rigidbody2D plrBody;
    private float horizontalDirection;
    private bool directionChanged => (plrBody.velocity.x > 0f && horizontalDirection < 0f) || (plrBody.velocity.x < 0f && horizontalDirection > 0f);



    // Raycast Functions

    private void CheckCollisions()
    {
        isGrounded = Physics2D.Raycast(transform.position, Vector2.down * groundRaycastLength, groundRaycastLength, groundLayer);
    }



    // Player General Functions

    private Vector2 GetInput() => new Vector2(Input.GetAxisRaw("Horizontal"), Input.GetAxisRaw("Vertical"));

    private void MoveCharacter()
    {
        plrBody.AddForce(new Vector2(horizontalDirection, plrBody.velocity.y) * (movementSpeed * sprintMultiplier));

        if (Mathf.Abs(plrBody.velocity.x) > (maxMovementSpeed * sprintMultiplier))
        {
            plrBody.velocity = new Vector2(Mathf.Sign(plrBody.velocity.x) * (maxMovementSpeed * sprintMultiplier), plrBody.velocity.y);
        }
    }

    private void ApplyGroundDrag()
    {
        if (Mathf.Abs(horizontalDirection) < 0.4 || directionChanged)
        {
            plrBody.drag = linearDrag;
        } else
        {
            plrBody.drag = 0f;
        }
    }


    // Player Mechanical Functions

    private void ApplyAerialDrag()
    {
        plrBody.drag = aerialLinearDrag;
    }

    // This might be another issue, the velocity after the execution would be (0, 5000) and not changing it's value.
    private void Jump()
    {
        plrBody.velocity = new Vector2(plrBody.velocity.x, 0f);
        plrBody.AddForce(Vector2.up * jumpForce, ForceMode2D.Impulse);
        print("Jumped!");
    }

    // This is (what i believe is) part of the issue.
    private void FallMultiplier()
    {
        if (!isGrounded)
        {
            if (!Input.GetKey(KeyCode.Space) && !isGrounded)
            {
                print("FallMultiplier");
                plrBody.gravityScale = fallMultiplier;
            }
            else if (Input.GetKey(KeyCode.Space))
            {
                plrBody.gravityScale = lowFallMultiplier;
                print("LowFallMultiplier");
            }
        }
        else
        {
            plrBody.gravityScale = 1f;
        }
    }

    // Initialized Functions

    private void Awake()
    {
        plrBody = GetComponent<Rigidbody2D>();
        baseMaxMovementSpeed = maxMovementSpeed;
        baseMovementSpeed = movementSpeed;
    }

    private void FixedUpdate()
    {
        CheckCollisions();
        MoveCharacter();
        if (canJump) Jump();

        if (isSprinting)
        {
            maxMovementSpeed *= sprintMultiplier;
            movementSpeed *= sprintMultiplier;
        } else
        {
            maxMovementSpeed = baseMaxMovementSpeed;
            movementSpeed = baseMovementSpeed;
        }

        if (isGrounded)
        {
            ApplyGroundDrag();
        } else
        {
            ApplyAerialDrag();
            FallMultiplier();
        }
    }

    private void Update()
    {
        horizontalDirection = GetInput().x;
    }

    private void OnDrawGizmos()
    {
        Gizmos.color = Color.red;
        Gizmos.DrawLine(transform.position, transform.position + Vector3.down * groundRaycastLength);
    }
}