Combining Bump and Normal maps causes weird reflections, change in colour brightness and flat shading (color space is set to "Non-Color Data") : r/blenderhelp
shaders - Flat shading due to normal map. Why? - Blender Stack Exchange
uv - Normal Map shades the object flat - Blender Stack Exchange
Tutorial : How to bake nice normal maps in flat-shading for low-poly mesh . - Tutorials, Tips and Tricks - Blender Artists Community
Problems using normal map and cycles (shading going to flat?) - Materials and Textures - Blender Artists Community
What Is The Difference Between Smooth Shading And Flat Shading? – blender base camp
Smooth vs Flat performance - Which answer is right? - Unity Forum
Blender 2.8 / 2.80 BAKING NORMAL MAP / SHADING / HARD EDGES - YouTube