I think I have found a bug. It is in typing "The Art of War".
The "s" in the first sentence of "Sun Tzu said:" does not want to be recognized. My "s" key works fine in other contexts, and other letters before this one are recognized just fine.
EDIT: Actually, this seems to happen for different books, relatively early on in each. I am also seeing it in "Grimm's Fairy Tales."
I have a MBP 2020, and I am using Safari.