Comment by kube-system

> if another Firefox user comes they are indistinguishable from each other,

Even if every Firefox browser gave off the exact same fingerprint, that wouldn't make the network traffic indistinguishable between Firefox users. There is a lot of entropy that is provided by your network stack of your device, the networks you connect to in order to get to the end website, the behavior of your requests, etc.

Now, most websites aren't doing this kind of analysis. But it isn't unheard of or impossible. There are major websites that are known to do TLS fingerprinting.