The showrunners aren't following the book very closely at all. They're just kinda adding their own plotlines, character relationships, characterization, etc, and using "well the book is an unreliable history" as an excuse as if the book didn't give three competing narratives and enough information for a reader to figure out what's probably true and what's definitely not. They've taken it from "here's an unreliable history, puzzle it out" to "this history is unreliable, so let's just write whatever we want."
Also in the final episode
cw sexual violence
There is a really awful scene where a character talks about all the abuse she suffered, and the other character responds by making out with her. This was not in the book, there is nothing like it anywhere in the book, none of the three narratives have it make any sense, and it was in fact an unscripted scene that the actresses just wanted to do.
Haven't watched the show but the book was pretty good and the show ruined some of the most impactful scenes.
Also Philosophy Tube plays a pirate who has been changed to a trans man with a cuckold fetish and gets way too much screentime. It was very confusing.
Also she didn't like the idea of playing a pirate that does horrible things and comes from a society where slavery is the norm...being a bad person. She had the writers make it clear that all those wives are fully consenting when their pirate lord husband pimps them out. Can't have a bad guy be a bad guy.
Edit: oh! And when she's introduced, a character literally asks her if she's a philosopher. Like real on the nose.