Fix : Window effects not working

I was experiencing square borders, no transparency, I tried to reactivate it on Control Center, reboot, or logout. Nothing worked

Doing some research I found this topic on Manjaro Forum experiencing the same problem as I, had many workarounds, and the first that I used worked (for now, I don’t know if I reboot it will happen again)

How to resolve it
Go to ~/.config and delete kwinrc

Now it should be working