因为你使用的是直接的阿尔法图像，所以骨架需要额外的材质，用于具有Additive混合模式的槽位。然而，SkeletonGraphic 组件在默认情况下只能使用一个纹理，所以你需要在 SkeletonGraphic 组件的检查器中启用 Advanced - Multiple CanvasRenderers 。请参阅spine-unity文档的以下部分。
[url=http://zh.esotericsoftware.com/spine-unity#%E9%AB%98%E7%BA%A7

%E5%8D%95%E9%A1%B5Texture-Atlas%E6%96%87%E4%BB%B6%E7%9A%84%E5%AF%BC%E5%87%BA%E5%92%8CSkeletonGraphic]spine-unity 运行时文档: 高级 单页Texture Atlas文件的导出和SkeletonGraphic[/url]

Since you are using a straight alpha image, the skeleton needs additional material for slots which have Additive blend mode. However, the SkeletonGraphic component is limited to a single texture by default, so you need to enable Advanced - Multiple CanvasRenderers at the SkeletonGraphic component Inspector. Please see the following section of the spine-unity documentation:
[url=http://zh.esotericsoftware.com/spine-unity#%E9%AB%98%E7%BA%A7

%E5%8D%95%E9%A1%B5Texture-Atlas%E6%96%87%E4%BB%B6%E7%9A%84%E5%AF%BC%E5%87%BA%E5%92%8CSkeletonGraphic]spine-unity 运行时文档: 高级 单页Texture Atlas文件的导出和SkeletonGraphic[/url]