I tried exporting the Spine file in Bleed mode and importing it into Unity.
The Unity version is 2022.3.9f1, and I'm using the Spine 4.1 package.
Following the official documentation, I checked the sRGB and Alpha is Transparency options on atlas, and also Straight Alpha Texture option on material.
However, when rendering in UI mode (SkeletonGraphic), there are display issues, but seems to be normal with SkeletonAnimation.
I've already tried changing the AtlasTextureSettings and Material settings in Preferences to StraightAlpha versions.
And also attempted to modify the Material in DefaultBleedSetting, but it still didn't work.