My own comment deeper in the tree made me realize something, so I'm restating it at the top level. Basically the central misconception here, that Google is more than happy to leave unclear, is that Incognito Mode has ever been incognito. The only party not gathering data about your "incognito" browsing is you, i.e. the only party to whom that browsing is incognito (unknown), is you. (Oh and anyone who were to use your computer and your login to view your browsing history; that's the flimsy pretext that prevents it from being a complete lie.)
In my other comment I joked that since you're basically wandering around forgetting where you've been, it should be called Forgetful Mode, and the icon should be, instead of a spy, an old man hunched over with a cane and little dots and curliques surrounding his head indicating a diffuse cognitive state. He doesn't remember where he's been! But don't worry, his caretakers will remember.
In my other comment I joked that since you're basically wandering around forgetting where you've been, it should be called Forgetful Mode, and the icon should be, instead of a spy, an old man hunched over with a cane and little dots and curliques surrounding his head indicating a diffuse cognitive state. He doesn't remember where he's been! But don't worry, his caretakers will remember.