how do i stop unity from keeping my button pressed?

i have a basic car controller script, the thing is whenever i hold th w or s keys for too long unity just keeps holding those keys for how long i pressed them. I also can not do brake i that time.

this is my script:

 using System;
 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 
 public class CarController : MonoBehaviour
 {
 
     [Header("Transforms")]
     [SerializeField] private Transform fronLeftT;
     [SerializeField] private Transform fronRightT;
     [SerializeField] private Transform rearLeftT;
     [SerializeField] private Transform rearRightT;
     
     [SerializeField] private WheelCollider frontleftC;
     [SerializeField] private WheelCollider frontRightC;
     [SerializeField] private WheelCollider rearleftC;
     [SerializeField] private WheelCollider rearRightC;
 
     [SerializeField] private float motorForce = 100f;
     [SerializeField] private float maxSteeringAngle = 50f;
     [SerializeField] private float breakForce = 100;
 
     private float steering;
 
     private float horizontalInput;
     private float verticalInput;
 
     bool isBraking;
     
     // Call Methods
     private void FixedUpdate()
     {
         GetInput();
         accelerate();
         steer();
     }
 
     // Steer
     private void steer()
     {
         steering = horizontalInput * maxSteeringAngle;
         frontleftC.steerAngle = steering;
         frontRightC.steerAngle = steering;
     }
 
     // User Input Method
     private void GetInput()
     {
         //get User Input
 
         horizontalInput = Input.GetAxis("Horizontal");
         verticalInput = Input.GetAxis("Vertical");
 
         // Initialize Break
         if(Input.GetKeyDown(KeyCode.Space))
         {
             isBraking = true;
             if(isBraking == true)
             {
                 breakCar();
             }
         }
         if(Input.GetKeyUp(KeyCode.Space))
         {
             isBraking = false;
             if(isBraking == false)
             {
                 frontleftC.brakeTorque = 0f;
                 frontRightC.brakeTorque = 0f;
                 rearleftC.brakeTorque = 0f;
                 rearRightC.brakeTorque = 0f;
             }
         }
     }
     
     // brake
     private void breakCar()
     {
         frontleftC.brakeTorque = breakForce;
         frontRightC.brakeTorque = breakForce;
         rearleftC.brakeTorque = breakForce;
         rearRightC.brakeTorque = breakForce;
     }
 
     // Accelerate
     private void accelerate()
     {
         frontleftC.motorTorque = verticalInput * motorForce;
         frontRightC.motorTorque = verticalInput * motorForce;
     }
 
 }