error CS0266: Cannot implicitly convert type 'float?' to 'float'. An explicit conversion exists (are you missing a cast?)

Question

I've never had this problem before. I keep getting this error:

error CS0266: Cannot implicitly convert type 'float?' to 'float'. An explicit conversion exists (are you missing a cast?)

Here's my code:

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.UI;
using System;
using LootLocker.Requests;
using TMPro;

public class XPManager : MonoBehaviour
{
    public static XPManager instance;

    string Collect50XP = "Collect50XP";

    public GameObject CollectXpButton;
    public Slider LevelSlider;
    public TMP_Text CurrentLevelTxt, NextLevelTxt, CurrentXpTxt, XpIncreaseAmount;

    private void Awake()
    {
        DontDestroyOnLoad(gameObject);
        if(instance == null)
        {
            instance = this;
        }
        else if (instance != this)
        {
            Destroy(gameObject);
        }
    }

    public void Collect50XpEvent()
    {
        LootLockerSDKManager.TriggeringAnEvent(Collect50XP, (response) =>
        {
            if (response.success)
            { 
                Debug.Log("Success");
                CheckLevel();
            }
            else
            {
                Debug.Log("Failed" + response.Error);
            }
        });
    }

    public void CheckLevel()
    {
        LootLockerSDKManager.GetPlayerInfo((response) =>
        {
            CurrentLevelTxt.text = response.level.ToString();
            NextLevelTxt.text = (response.level + 1).ToString();
            CurrentXpTxt.text = response.xp.ToString() + " / " + response.level_thresholds.next.ToString();
            if (LevelSlider.value == LevelSlider.maxValue)
            {
                LevelSlider.maxValue = response.level_thresholds.next - (float)response.xp - int.Parse(XpIncreaseAmount.text);
                LevelSlider.value = 0;                
            }
            else
            {
                LevelSlider.value = (float)response.xp - response.level_thresholds.current;
            }
        });
    }
}

It's coming from this line:

LevelSlider.maxValue = response.level_thresholds.next - (float)response.xp - int.Parse(XpIncreaseAmount.text);