This is the userscript I used to defeat my school's blocking system. No joke, it worked.

defeatblocking.user.js

// ==UserScript==
// @name         Unhide Sites
// @version      1.0
// @author       tacohitbox
// @match        *://*/*
// @icon         https://upload.wikimedia.org/wikipedia/en/thumb/9/9a/Trollface_non-free.png/220px-Trollface_non-free.png
// @grant        none
// ==/UserScript==

if (document.title == "Page Blocked") {
    if (window.location.href.substring(0, 5) == "http:") {window.open(`https:${window.location.href.substring(6)}`, "_self"); return;}
    request(window.location.href, "full");
}

function request(url, type) {
    var x = new XMLHttpRequest();
    x.open("GET", url);
    x.setRequestHeader("Sec-Fetch-Dest", "image");
    x.send();
    x.onload = function() {
        if (type == "full") {document.querySelector("html").innerHTML = x.responseText;}
        else {return x.responseText;}
    }
}