[Dylan16807]

That's not the only way it could be done.

But sure, sending that extra tidbit of information specifically to servers that they can verify won't track you would be a good tradeoff.

Even worse is that they probably do try to detect if you're in an incognito session, but only for their benefit.

Edit: Here's an easy thing they could do. Even if we accept or pretend to desire cross-browser correlation at all, new-seeming browser profiles could have their information siloed for a few days and if they disappear in that time it all gets treated as an incognito session.