Arch Linux is a rolling release distribution.

It's a good idea to rebuild all third party packages after the system is updated, since they may expect libraries that are now out of date.
Rebuild all AUR packages using yay: pacman -Qqm | yay -S -

For styling QT and GTK programs similarly, see the arch wiki: https://wiki.archlinux.org/title/Qt#Configuration_of_Qt_5/6_applications_under_environments_other_than_KDE_Plasma
You need to set the env variable QT_QPA_PLATFORMTHEME=qt5ct. Make it system-wide by editing /etc/environment

As a base, Luke Smith's voidrice (https://github.com/LukeSmithxyz/voidrice/) is very useful. Most of localxen is modeled around his environment, so kudos.