github-negative-emoji-blocker.js

// ==UserScript==
// @name         GitHub Negative Emoji Blocker
// @namespace    http://tampermonkey.net/
// @version      0.1
// @description  Block negative emojis on GitHub
// @author       You
// @match        *://github.com/*
// @grant        none
// ==/UserScript==

(function() {
  'use strict';
  const blockedEmojis = ['-1', 'thinking_face'];

  const disableEmojis = () => {
    document.querySelectorAll("button[data-targets='reactions-menu.menuItems']") .forEach(item => {
      const emoji = item.querySelector('g-emoji').getAttribute('alias');
      if (blockedEmojis.includes(emoji)) {
        item.style.opacity = '0.2';
        item.style.pointerEvents = 'none';
      }
    });
  };

  const observer = new MutationObserver(disableEmojis);
  observer.observe(document.body, { childList: true, subtree: true });

  disableEmojis();
})();