@choihyunji Which version of the Spine URP Shaders UPM package are you using? You can find the version in the Package Manager window in Unity, or tell us the name of the zip package that you have downloaded.
If you're not using the latest version of the package, please have a try whether updating it resolves your issue.
If the issue persists with the latest package, could you please show how exactly your ambient light settings are (using an IBL skybox, or 3-color-gradient ambient light, etc.) that provide light in the shaded areas? You could alternatively also send us a minimal Unity project that demonstrates this issue as a zip package. You can send it to contact@esotericsoftware.com, briefly mentioning this forum thread URL so that we know the context. Then we can have a look at it.
