PSA: Watch in an private/incognito tab/window. If you are currently logged into your google account, this WILL pollute your watched history: https://www.youtube.com/feed/history
Netflix, Amazon, Youtube, PornHub, etc... they're all accomplishing little more than "similar to the one, and only one item you last saw", with dramatic shifts in "profiling" from one or two videos.
Actually, Netflix acknowledges this and splits the recommendation into "because you watched X..", so at least it covers a greater range (eg last 5 things seen)
I'm damned sure they could be much more useful if they would let me tell them what I like, by implementing rating systems that are worth using (e.g. the ability to browse and edit previous ratings in a sane fashion)
but user-useful recommendation is not the actual goal, so really its just that our metrics are wrong. It's probably great according to view counts.