Tiny enough to paste the whole thing here. Clever trick to insert a "." after the .com that seems to trick some of the ad targeting. Wonder how many other sites this works on?
chrome.tabs.onUpdated.addListener(function (tabId, changeInfo, tab) {
if (changeInfo.status === "loading" && /youtube.com/.test(changeInfo.url)) {
let url = new URL(tab.url);
if (!url.hostname.endsWith(".")) {
url.hostname = url.hostname + ".";
chrome.tabs.update(tabId, { url: url.href });
}}})