This will remove the giveaways already entered in Steam Gifts

SteamGiftsEnhancer.user.js

// ==UserScript==
// @name         Steam Gifts Enhancer
// @description  This will remove the giveaways already entered in Steam Gifts
// @version      1.0.2
// @author       gonza7aav
// @match        https://www.steamgifts.com/
// @match        https://www.steamgifts.com/giveaways/
// @match        https://www.steamgifts.com/giveaways/search?*
// @grant        none
// @run-at       context-menu
// @iconURL      https://cdn.steamgifts.com/img/favicon.ico
// ==/UserScript==

(function () {
  'use strict';

  // get all the giveaways from the page
  const allGiveaways = [
    ...document.querySelectorAll('.giveaway__row-outer-wrap'),
  ];

  // filter the entered
  const enteredGiveaways = allGiveaways.filter((x) =>
    x.children[0].className.includes('is-faded')
  );

  // remove them
  enteredGiveaways.map((x) => x.remove());
})();