@MXXXXXS In addition to what Spinebot already mentioned, what shader are you using at the Spine skeleton, what are the material settings?

Please make sure you're using shaders from the Spine URP Shaders UPM package (or other URP compatible shaders) with your skeleton when using URP in your project. Also be sure not to use 2D URP shaders when using a URP 3D Renderer, and vice versa.

See details here:
https://esotericsoftware.com/spine-unity#URP-Shaders---Extension-UPM-Package