It sounds like you're thinking of window.navigator.webdriver, which is a WebDriver thing not part of Chrome DevTools Protocol. With CDP, as far as I can tell the detection mechanisms are more about the heuristics of e.g. how fast a form is filled -- which this AI stuff will trigger immediately too.

(And even if CDP had an explicit marker somewhere, surely patching that out is easier than piling up enough patches to "make a new browser".)