Hi, i am new here.

I just fresh installed archlinux using lxqt and kwin. Looking new experiences with kwin as WM. I used i3 before this.

btw i notice something weird on kwinrc. At kwinrc OpenGLIsUnsafe keep return to "true" when reboot.

It disable "Present Windows" effect.

normally i just edit the value to OpenGLIsUnsafe=false, then do logout and re login.
But if i reboot or power on the pc, it goes back to true value.

Probably has to do with your graphics setup. What card and driver are you using? What does it show under System Settings -> Display and Monitor -> Compositor -> Rendering Backend?

Does kwin actually respond to your changing the kwinrc and enable compositing effects? I would expect that if it is automatically reverting that value that it either isn't picking up the change (and just overwriting whatever changes had been made when you log out) or it's continuing to determine that open GL is unsafe (according to whatever criteria it uses for that determination).