Let's start with the question about whether color_srgb_to_scene_linear is correct. Vertex colors in glTF are supposed to be linear, and I'm fairly confident Blender's Python API is returning sRGB ...

Can you provide a sample? From your description even a blender 3.5 gltf default cube will fail. If I remember correctly a empty scene will fail to import into godot engine regardless of version.

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