Spatial denoise uses shader specialization. The current shader had
this disabled for OpenGL and Vulkan. As OpenGL and Vulkan supports
shader specialization it is fine to enable them. Would result in
better optimized shaders.
I checked other shaders as well. This was the only one ignoring shader
specialization.
Pull Request: https://projects.blender.org/blender/blender/pulls/126830
8e80cfdfd9