Update broke Qt5 theming using qt5ct and Kvantum

Today i updated my system, including the package qt5-styleplugins from aur.
After some time i opened a Qt5 program (kid3, later kdenlive) and there was no theming (it reverted to default, with manually selected gtk2 theming making kdenlive crash).

Im using Gnome as a desktop.
Troubleshooting made me discover qt5ct no longer recognized my .profile (i had it set up to use gtk2 theming), so i tried to delete the config and put the qt platform theme again, but no effect. I tried to switch the theming to Kvantum, just to find the same kind of issue.

EDIT: entering a Gnome Wayland session makes qt5ct and kvantum not work, otherwise it works under X11.
Not even the change in /etc/envoirment helped

After checking /etc/enviorment , i found that QT_QPA_PLATFORMTHEME was set on qt5ct and QT5_STYLE_OVERRIDE was set on kvantum, causing an incompatibility making qt5ct not work properly.

So, the real issue is Qt theming under Wayland. If so, you might want to change the topic title, to be helpful for future readers and for forum searching.

Do you mean that the update brought new values in the file, without creating backup files (.pacnew, .pacsave, etc.)?
Was the file edited/changed in the past by you?

On wayland sessions, (bash, X, etc.) dot files are not parsed/read, so you have to pass environment variables (usually set in .profile, etc.) to the session in another way.
IIRC, with a service that would import environment to systemd, or using $XDG_CONFIG_HOME/environment.d/. Read all methods at Archwiki.