When I use a fast pass, the amount of text in the new chapter basically doubles from the 6 lines or so I can see before purchase. I can't see the rest of the chapter, either directly or by scrolling. If I refresh the browser page, I can see the whole chapter, but am positioned at the end (or even in the book comments) and have to scroll back up to the beginning.
Google Chrome Version 87.0.4280.141 (Official Build) (64-bit) on Linux Mint.
Page options within WebNovel are Night mode (black background), Roboto font.
Other UI comments:
I in general like the chapter reader (font options, background option, amount of text on screen).
Often the first click on the go to previous chapter arrow of the options page doesn't change anything, but clicking it one more time goes back two chapters.
I'd prefer something direct for going back to the library instead of the top going to previous screen arrow on the options page. At least once clicking on the arrow didn't take me back to the library but instead to other chapters (have not replicated this yet).
Size of icons in the library, and lack of new chapter notifications are things you know about. I would prefer to still see the number of chapters read/exist but I can understand reasons for not including it.