reflections look pixelated in render-result:
116841
Reflection is quad dependent and looks non realistic
8205
Transparent textured planes produce black artifacts
757
How do I avoid rendering glitches from overlapping faces?
106180
How can I fix this jagged Shadows?
44627
Can I use an HDRI for reflections only, and not have its light affect the scene?
121397
Why is my render noisy/blotchy?
89032
What is causing the edges of my models to become semi-transparent?
100602
Black reflections at extreme angles with glossy shader on smooth surfaces
154227
Cause of Alpha or Black Artefacts in Render
101435
Black reflections with Cycle's Glossy Material
76067
What's wrong with my render?
130276
Cycles: How do I exclude the Environment Texture from reflections?
16819
Why does my scene preview look so different than the render?
3565
Why does mesh behave like mirrored in Edit mode without Mirror modifier?
26477
Object looks fine in rendered mode, but appears black in material mode
61325
Blender Cycles Bake Not Looking Like Object in Rendered View
53668
I'm using a high number of samples. Why is my render coming out in low quality?