The necessary runtime requirements for Imager are pretty standard Qt 6 libraries, and Pacman takes care of these for you. Just run:
sudo pacman -S rpi-imager
This will install:
sudo pacman -S qt6-wayland # to fix a blank window issue on Wayland
sudo pacman -S kvantum-qt6 # if you really want Kvantum for your Qt6 apps
sudo pacman -S qt6ct # to manage your Qt6 themes more easily
If you want to keep your global Kvantum settings but still make sure Imager launches properly:
mkdir -p ~/.local/share/applications
cp /usr/share/applications/org.raspberrypi.rpi-imager.desktop ~/.local/share/applications/
nvim ~/.local/share/applications/org.raspberrypi.rpi-imager.desktop
Exec=env -u QT_STYLE_OVERRIDE -u QT_QUICK_CONTROLS_STYLE rpi-imager /usr/bin/rpi-imager %F
- update-desktop-database ~/.local/share/applications 2>/dev/null || true