no-duck-ai.user.js

// ==UserScript==
// @name         Block DuckDuckGo's AI
// @namespace    http://tampermonkey.net/
// @version      1.0
// @description  Add kbg=-1 and kbe=0 to DuckDuckGo URLs if missing
// @author       qgustavor
// @match        *://duckduckgo.com/*
// @grant        none
// @installUrl    https://gist.github.com/qgustavor/c2dba88fdec3d2383310b1503d766065/raw/no-duck-ai.user.js
// @updateUrl    https://gist.github.com/qgustavor/c2dba88fdec3d2383310b1503d766065/raw/no-duck-ai.user.js
// ==/UserScript==

const newUrl = new URL(window.location.href)
const params = newUrl.searchParams
let needsReplace = false

if (!params.has('kbg')) {
  params.set('kbg', '-1')
  needsReplace = true
}
if (!params.has('kbe')) {
  params.set('kbe', '0')
  needsReplace = true
}

if (needsReplace) {
  window.location.replace(newUrl.toString())
}