Operating system: Windows-10-10.0.18362 64 Bits
Graphics card: GeForce GTX 970/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 430.86
Broken: version: 2.81 (sub 15), branch: master, commit date: 2019-10-11 19:43, hash: rB60d02b336eaf
Short description of error
Bump node ignoring smooth shading when generating normal map.
As you can see, this cube's map is faceted, but in shade smooth is active.
Naturally, after subdividing it, facets become smaller, but it's still not a smooth gradient, as expected:
Exact steps for others to reproduce the error
Just open it and switch to Rendered or Lookdev