now THIS is something I'd love to see a HN or blog post about...

edit: A google search brings me to this. https://www.blackhatworld.com/seo/my-bot-has-stopped-working...

Seems it is from twimg, which I believe is the image host used for tweets with images attached? I wonder why they can't revoke this.

And interestingly, the js file linked in that forum post is still alive... https://abs.twimg.com/k/en/init.en.37d4e85afd8ede9741dd.js