Why looks like this?

[camy (Camelia)]

I rendered in Cycles. What’s wrong?

[Andreal (Andrzej)]

Check geometry, maybe there is something hidden in viewport but visible in render view and it is overlapping with wall.

[Secrop]

Moved to Support > Basics & Interface.

@Andreal might be right about this one. It looks like a ZBuffer conflict with some hidden geometry (not hidden in render).