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
It all goes back to Proctor & Gamble. They sell you stuff and drive much of the advertising and tracking technology on the web. They have been at influence buying since people yelling from soapboxes along the riverfronts. They are in some part behind just about every influence and online trackin technology today.