I always watch logged-out. (Occasionally on iOS I will be unknowingly logged-in, not sure how that happens. I log out if I notice I am logged-in.) YouTube seems

I always watch logged-out. (Occasionally on iOS I will be unknowingly logged-in, not sure how that happens. I log out if I notice I am logged-in.) YouTube seems to maintain an identity for me, and auto-constructs playlists using past items viewed. Recommendations appear to relate to past viewing. I’m uncertain on how cookies are maintained. Are these Safari cookies behind the scenes? My point is, contrary to GP’s claim, there is some mechanism for viewing history even if it is turned off.