Ask HN: How much do advertisement "partners" pay to publishers?

Hi. In the EU, these so-called "cookie banners" are very well known and a common sight when visiting almost any website.

Some of these banners also include the list of all "information partners", i.e. some companies where user data are sent to.

Now this list is normally huge: A small news outlet or blog can have more than 500 "partners" the names of which I have almost never heard. Some of them also employ dark-ish patterns such as not allowing you to deselect them all at once, or even better, having all of them deselected except some seemingly random ones, making the user scroll all the way to be able to see al selected ones, further annoying them.

All of this makes me wonder, why do publishers go through all this? Is the money that significant, compared to other ways of showing ads? Can someone provide some concrete numbers, maybe on a per-visitor basis? Can anyone provide light on these partners, their business modesl, and whom they sell the collected data to?

Thanks