Does the script attempt to run though? If linkedin runs this and other scripts it would explain why the site is so bloated.

Yea, well that was my first though, but then I though - why would chrome even allow any website to just arbitrary check which extensions you have installed.

So I checked the scripts and at this line the script is showing

async function fetchExtensionInfo(extensionId) {
  return new Promise((resolve) => {
    const url = `https://chromewebstore.google.com/detail/$%7BextensionId%7D`;

So I thought maybe they were calling the chromewebstore foreach plugin, and if you have an extension already installed, you get a different response than when you don't - or something.

But I suppose I'm wrong and for some reason a site can just ask the browser internally which plugins are installed