shorts-redirect.user.js

// ==UserScript==
// @name        Youtube shorts redirect
// @namespace   Violentmonkey Scripts
// @match       *://*.youtube.com/*
// @grant       none
// @version     1.0
// @author      belst
// @description 9/22/2022, 1:26:47 PM
// ==/UserScript==

let href = window.location.href;

const redirect = () => {
  if (href.includes('/shorts')) {
    window.location.replace(href.replace('/shorts/', '/watch?v='));
  }
}

redirect();

window.onload = () => {
  const observer = new MutationObserver((mutations) => {
    for (const m of mutations) {
      if (href !== window.location.href) {
        href = window.location.href;
        redirect();
      }
    }
  });

  observer.observe(document.body, {childList: true, subtree: true});
};