Qt6 means most likely sticking with C++ (and that's what the Budgie Display Configurator is written in, looking at the forge). With other high profile projects like KDE and Hyprland also being written in C++, the movers and shakers of the modern FOSS DE landscape seem to be somewhat indifferent to the folk wisdom (at least judging by some online communities) of C++ being "legacy" tech.
Just an observation. I'm not into language advocacy. 😅