OpenAI's ad collector at bzr.openai.com sets a cookie called __obi, scoped to .openai.com. The value is while you are on ChatGPT and tied to your ChatGPT account. __obi is then sent to OpenAI from ordinary websites you visit.
Any company that buys ads on ChatGPT installs
Is it a new tracker? Does it apply to the app only?
As per the article, it is by itself not a new technology. Meta has been using this for years and is standard in the industry. So I’d wager most respectable browsers would have tracking prevention that stops this.
What is new, and what this article talks about, is that ChatGPT can attach your browsing habits to things you’ve shared with ChatGPT itself. As in, possibly very private details about you and your life.