I dislike YouTube as much as the next person, but do you understand how unreasonable of an ask this is when you are explicitly going into incognito mode? I echo everyone else's sentiment here.

I don't know why everyone is fixated on the term incognito. I believe what GP wants (and me too) is to pause watching history or to at least exclude a viewing session from the recommendation algorithm.

Let's discuss this feature some more?

The reason users such as yourself want this feature is because you don't have faith in the recommendation algorithm, right? If you watched a video and Google started pushing related videos that you don't want to constantly see, and you clicked on the "do not recommend this kind of video" option, and it /actually/ worked, would you be satifised without this "exclude from recommendation algorithm" mode?

If so, the better solution here would be to have a recommendation system that isn't garbage. I admit I kind of fancy this described mode, but the only reason is because I don't currently trust Google to actually respect my expressed discontent. And if we don't trust Google to have a faithful recommendation system, why would we be willing to trust YouTube Premium?

If that bit is a literal bit, there will be an extension that just sets that bit, thereby bypassing ads when you didn't actually pay a subscription.

If that bit is some sort of encoded identifier that an extension couldn't generate, then they will know who you are.