System Information
Operating system: Windows 10
Graphics card: Geforce 3070

Blender Version
Broken: 3.1.2
Worked: 3.0

Short description of error
Geometry that was very close together previously rendered OK in Cycles in Blender 3.0. Since Blender 3.1 (also tested Blender 3.2) Cycles displays black banding artefacts on this close z - fighting geometry.
Cycles in GPU (Optix) or CPU mode produces the same result.

Exact steps for others to reproduce the error
Create overlapping geometry and render in cycles.

Blender 3.0

Blender 3.2