I may be in the minority but I disliked the ending, not because I wish it was open-ended, but because I wish Kya had not done it. I felt like so much of the book was not just about the marsh and about the need to survive, but also about empathising with Kya, loving her for who she is. That ending, to me at least, went against that, by making her appear to be a lot more cold-blooded than I thought she was, murdering less out of self-defence and more out of vengeance, or if not that then at least hiding it well enough to lie to and get acquitted by a court of law. I get that she had no choice but still, I felt this was thrown it at the end to respect the rules of the whodunnit, it didn't feel natural to me, and it went against who I felt she was. I saw some disagreements on that on other threads too, happy to hear opposite opinions 😊