I find these fake progress bars a borderline-dark pattern: in general, the goal is to deceive users into waiting for progress that isn't truly happening, with the goal of holding their eyeballs.
How is this "fake"? I can set the exact percentage of the progress bar.
It’s fake because even after you set the exact correct percentage of the progress bar, the progress bar still keeps moving forward on its own, even if your process hasn’t made any progress. The page says it itself: NProgress has “realistic trickle animations to convince your users that something is happening” – even if nothing is actually happening. The stuttering-forward is all about looking like something is happening, when it that is not necessarily true.