Using optix flattening the render materials
Maybe explain in more detail what you did to arrive at these images.
First provide the necessary information about your system and software configuration to know what that was run on:
OS version, installed GPU(s), VRAM amount, display driver version, OptiX (major.minor.micro) version, CUDA toolkit version (major.minor) used to generate the input PTX, host compiler version.
Then explain the OptiX denoiser setup used in the left image.
Provide the original input image(s), best in EXR format.
The exact source code with all the denoiser related code and parameters would be helpful, or a complete and minimal reproducer project.
Depending on which OptiX version and denoiser mode you used (HDR, AOV), did you calculate the HDR intensity and average color correctly?
https://raytracing-docs.nvidia.com/optix7/guide/index.html#ai_denoiser#nvidia-ai-denoiser