i really don’t know what could be. there are no 2 planes, it is only one, model is from Archi CAd
This looks like too low UHD cache settings. Could you look to render setup>performance>uhd cache and tell what value is precision set to.
I’m sorry i got settings from client but obviously they weren’t good. I just put back everything to default. now the image looks really clear but i still have some weir gradient on walls. i am using a texture in diffuse which i was given by the client. what that gradient could be? i have only 1 corona light directly over the apartment
It’s hard to say without having scene itself. Could be some invisible light, or low quality texture of the wall.
I am not sure, but it looks like there is heavy denoising used in this render. This could cause such artifacts, so the solution would be to render for a bit longer, and then apply lower denoising.