When I add Filter mask or Filter Layer and want to tweak Properties as soon as I open that dialog Krita tone down canvas, like some color overlay. Can I disable that? I mean how can I tweak color if Krita adds some color overlay over canvas .. Is this Krita or KDE thing? I am using latest KDE Neon.

It's a kwin thing. Check the window manager effects settings.

Thanks for answer, found it. Works now.