Sailer I'll add a bit more detail to Spinebot's answer. You mentioned you're using Unity 6. Actually, Unity now sets the default color space for new projects to Linear. Because of this, if you output texture atlases using Spine's default settings, they become incompatible with Unity's default configuration. (Spine's Texture Packer settings use Premultiplied Alpha (PMA) by default, but PMA textures cannot be used in Linear color space.)
If you want to match your skeleton settings to Unity's default, please use the solution recommended by Spinebot. If you want to match the Unity project to the skeleton's textures, please change the project's color space to Gamma. For more details, refer to the following section in the documentation:
spine-unity 运行时文档 资产 #进阶操作 - Premultiplied和Straight Alpha导入
