I'm sure you have heard it before. Some show or movie on Netflix had millions and millions of viewers in the first week or month. It's an arbitrary measurement that Netflix setup itself to bolster it's own shows and movies.
Previously Netflix would start calling a show or movie you watched as "viewed/watched", in it stats, after you got through 70% of the movie or 70% of the 1st episode if it was a series. At the time it made some sense. Because if you watch just a couple minutes of a movie you really didn't "watch" it, right?
Well, now Netflix has changed their stats. Now the new metric for counting a movie or show as "watched/viewed" is when you play something for 2 minutes. If this is a 5 minute comedy special then fine makes sense I guess. But if this is a 3 hour movie, watching only 2 minutes does not count as being "watched" by most people. Let's take The Witcher for example. Each episode ranges from 47 to 67 minutes. So lets call it 57 minutes. So if you watched 3.5% of an episode (or 2 minutes) then Netflix will count you as a viewer of the show. Seems crazy right?
Well it is. Netflix just happened to change its viewership metrics when it released the viewers for 6 Underground (movie) and The Witcher (tv show).
6 Underground counts for 83 million views

The Witcher counts for 76 million views

According to the old, more reliable stats, here is more viewership data
Orange is the New Black = 105 million views
Murder Mystery = 73 million views
Stranger Things Season 3 = 64 million views
Bird Box = 45 million views
The Umbrella Academy = 45 million views
Now my theory is that less people watched The Witcher and Underground 6 as they expected or wanted and so have changed their own metrics to make it sound better. I mean Netflix is a business and needs to keep people happy and making money and subscribing so I get it. But come on Netflix if I watch 2 minutes of The Irishman I did NOT watch it.
So moral of the story: When a company releases information based on their own metrics; take it with a grain of salt.