Can someone explain the point in the article that Facebook can still track you if the script is loaded from an edge cache and the browser doesn't send cookies?

Can someone explain the point in the article that Facebook can still track you if the script is loaded from an edge cache and the browser doesn't send cookies? I can think of unique script URLs, but if it's coming from an edge cache, presumably it's not that unique. And maybe some sort of JS-based fingerprinting? But since Brave controls the browser, it's within their control to try to make the browser environment homogenous across users. I think Tor Browser does something like that, not sure about Brave. Any other attacks I'm not thinking of? edit: oh, if the script makes a request back to FB, then I suppose your IP address is available...