Wow — 5.9 million different versions of ads? That is incredible.
Trump ran 5.9 million different versions of ads during the presidential campaign and rapidly tested them to spread those that generated the most Facebook engagement, according to the paper. Clinton ran 66,000 different kinds of ads in the same period.
Independent of the politics, you should assume that whatever advertising message you are getting on the Internet you may be the only one getting it, and it may be targeted to take advantage of specific information known only about you. Also, run an ad blocker. I use 1Blocker.