The ratings/star filters have no effect. Images with star ratings can only be filtered using the "no rating" option. digiKam: 9.0.0 Appimage KDE Frameworks: 6.20.0 Qt: 6.10.1 Debian GNU/Linux 12 (bookworm) (Xcb) Kernel: linux 6.1.0-44-amd64 Operating System: MX Linux 23 KDE Plasma Version: 5.27.5 KDE Frameworks Version: 5.103.0 Qt Version: 5.15.8 Kernel Version: 6.1.0-44-amd64 (64-bit) Graphics Platform: X11
It must be already fixed in current 9.1.0 pre-release available here : https://files.kde.org/digikam/
Fixed with Bug 517420 Maik