ebay.co.uk doesn't have a blacklist feature - this tampermonkey script allows me to avoid buying from blacklisted sellers again

ebayblacklist.js

// ==UserScript==
// @name         Ebay Blacklist
// @namespace    https://www.cgtk.co.uk
// @version      0.1
// @description  Make it clear when ebay sellers are on a blacklist
// @author       A. Budden
// @match        https://*.ebay.co.uk/itm/*
// @icon         https://www.google.com/s2/favicons?domain=ebay.co.uk
// @grant        none
// ==/UserScript==

(function() {
    'use strict';
    // Put the blacklisted seller names in here:
    var blacklist = [
        'seller1',
        'seller2',
        'seller3',
        'seller4',
        'seller5'
    ];

    var sellerObjs = document.getElementsByClassName('ux-seller-section__item--seller');
    var foundSeller = false;
    for (var sellerObj of sellerObjs) {
        var subElements = sellerObj.getElementsByClassName('ux-textspans ux-textspans--PSEUDOLINK ux-textspans--BOLD');
        for (var subElement of subElements) {
            var seller = subElement.innerHTML;
            if (blacklist.indexOf(seller) === -1) {
                return;
            }
            foundSeller = true;
            sellerObj.innerHTML = '<span class="blacklistBanner"><font color="red">BLACKLISTED!</font> </span>' + seller;
        }
    }
    if ( ! foundSeller) {
        return;
    }

    var titleObj = document.getElementsByClassName('x-item-title__mainTitle')[0];
    titleObj.innerHTML = '<span class="blacklistBanner"><font color="red">BLACKLISTED SELLER!</font> </span>' + titleObj.innerHTML;

    var blink_speed = 250; // every 250 == 0.25 second
    var t = setInterval(function () {
        var eles = document.getElementsByClassName('blacklistBanner');
        for (var ele of eles) {
            ele.style.visibility = (ele.style.visibility == 'hidden' ? '' : 'hidden');
        }
    }, blink_speed);
 })();

Updated to match changes to ebay website.