Running kristall on gnome/wayland (default) generates the following warning:

 Warning: Ignoring XDG_SESSION_TYPE=wayland on Gnome. Use QT_QPA_PLATFORM=wayland to run on Wayland anyway.

If you try to set QT_QPA_PLATFORM=wayland without qtwayland5 package installed,
kristall will fail to launch. To fix it and run kristall natively on wayland,
please install the qtwayland5 package. For further info, refer to bug #1018251.