Unity Crashing when time slows

I’m participating in a Game Jam and made a Time Slow Powerup for the game. It was working, untill I added some new code and started crashing. The problem is, even after commenting it out, it still crashed.
You should know that I am using Unity 2019.4.17f1.

This is the Time Slow code:

void Items()
{
if(Input.GetKeyDown(KeyCode.T) && timeRecharged)
{
timeCanCancel = false;

        StartCoroutine(TimeSlow());
        while (timeIsSlow)
        {
            if (Input.GetKeyUp(KeyCode.T))
            {
                timeCanCancel = true;
            }
            if (Input.GetKeyDown(KeyCode.T) && timeCanCancel)
            {
                StopCoroutine(TimeSlow());
                Time.timeScale = 1f;
                timeIsSlow = false;
                StartCoroutine(TimeCancel());
            }
        }
    }
}
IEnumerator TimeSlow()
{
    timeRecharged = false;
    Time.timeScale = timeSlowAmount;
    timeIsSlow = true;
    yield return new WaitForSeconds(4f);
    Time.timeScale = 1f;
    timeIsSlow = false;
    yield return new WaitForSeconds(7f);
    timeRecharged = true;
}
IEnumerator TimeCancel()
{
    yield return new WaitForSeconds(4f);
    timeRecharged = true;
}

PS: Now i’ve got another bit of code that crashes unity:

if (Input.GetKeyDown(KeyCode.G))
{
Physics2D.gravity = new Vector3(0, -gravityStrength, 0);
}

…Note that i’m calling Items in FixedUpdate()