It seems to work in Firefox with Greasemonkey for me.
Here's the code I am using:

// ==UserScript==
// @name                 eBay - Hilight Items With Bids
// @namespace     http://userscripts.org/users/126140
// @include         https://*.ebay.*/*
// @include         http://*.ebay.*/*
// @grant       unsafeWindow
// @version     2.2.1
// @require         http://ajax.googleapis.com/ajax/libs/jquery/3.3.1/jquery.min.js
// @description Hilights items that have bids with a red border and yellow background.
// ==/UserScript==

(function() {

  var highlightBids = function() {

    $(".lvformat").each(function() {
      $this = $(this);
      var text = $this.text();
      var regExp = /([0-9]+)\s+(b|B)ids?/;
      if (regExp.test(text)) {
        var match = regExp.exec(text);
        var numBids = parseInt(match[1], 10);
        if(numBids > 0) {
          $this.closest('li.con-rst').css({"border":"3px solid red","background-color":"yellow"}); // Regular listing of articles
          $this.closest('li.li').css({"border":"3px solid red","background-color":"yellow"});  // Some search results are not shown in the above "regular" way
          $this.closest('div.box.mitem').css({"border":"3px solid red","background-color":"yellow"}); // Tiled search results
        }
      }
    });
  }

  var window_history_pushState = window.history.pushState;
  window.history.pushState = function () {
    window_history_pushState.apply(window.history, arguments);
    window.setTimeout(highlightBids, 0);
  }

  $(window).bind('popstate', function() {
    window.setTimeout(highlightBids, 1000);
  });

  highlightBids();

})();

Updated:

// ==UserScript==
// @name        eBay - Hilight Items With Bids
// @namespace   http://userscripts.org/users/126140
// @include     https://*.ebay.*/*
// @include     http://*.ebay.*/*
// @grant       unsafeWindow
// @version     2.2.1
// @require     http://ajax.googleapis.com/ajax/libs/jquery/3.3.1/jquery.min.js
// @description Hilights items that have bids with a red border and yellow background.
// ==/UserScript==

(function() {

  var highlightBids = function() {

    $(".s-item").each(function() {
      var li = $(this);
      var text = li.text(); 
      var regExp = /([0-9]+)\s+(b|B)ids?/;
      if (regExp.test(text)) {
        var match = regExp.exec(text);
        var numBids = parseInt(match[1], 10);
        if(numBids > 0) {
          li.css({"border":"3px solid red","background-color":"yellow"}); // Regular listing of articles
          li.closest('li.li').css({"border":"3px solid red","background-color":"yellow"});  // Some search results are not shown in the above "regular" way
          li.closest('div.box.mitem').css({"border":"3px solid red","background-color":"yellow"}); // Tiled search results
        }
      }
    });
  }

  var window_history_pushState = window.history.pushState;
  window.history.pushState = function () {
    window_history_pushState.apply(window.history, arguments);
    window.setTimeout(highlightBids, 0);
  }

  $(window).bind('popstate', function() {
    window.setTimeout(highlightBids, 1000);
  });

  highlightBids();

})();

Update:

// ==UserScript==
// @name        eBay - Hilight Items With Bids
// @namespace   http://userscripts.org/users/126140
// @include     https://*.ebay.*/*
// @include     http://*.ebay.*/*
// @grant       unsafeWindow
// @version     2.2.1
// @require     https://ajax.googleapis.com/ajax/libs/jquery/3.3.1/jquery.min.js
// @description Hilights items that have bids with a red border and yellow background.
// ==/UserScript==

(function() {

  var highlightBids = function() {

    $(".sresult").each(function() {
      var li = $(this);
      var text = li.text(); 
      var regExp = /([0-9]+)\s+(b|B)ids?/;
      if (regExp.test(text)) {
        var match = regExp.exec(text);
        var numBids = parseInt(match[1], 10);
        if(numBids > 0) {
          li.css({"border":"3px solid red","background-color":"yellow"}); // Regular listing of articles
          li.closest('li.li').css({"border":"3px solid red","background-color":"yellow"});  // Some search results are not shown in the above "regular" way
          li.closest('div.box.mitem').css({"border":"3px solid red","background-color":"yellow"}); // Tiled search results
        }
      }
    });
  }

  var window_history_pushState = window.history.pushState;
  window.history.pushState = function () {
    window_history_pushState.apply(window.history, arguments);
    window.setTimeout(highlightBids, 0);
  }

  $(window).bind('popstate', function() {
    window.setTimeout(highlightBids, 1000);
  });

  highlightBids();

})();