the changes for me are a no-op, its the app that changes, sadly it looks like the dev's for qbittorrent have given up detailing what goes into each release, last changelog entry was jan 2022:- https://github.com/qbittorrent/qBittorrent/blob/master/Changelog
im personally sticking on 4.3.9 for a while, it works well enough, but im sure it does have bugs too, slightly concerned by the 2,783 open issues though for qbittorrent 🙂