I don't know if this is a bug, but the material "Universal Render Pipeline/2D/Spine/Sprite" checking the "Tint" option turns the skeleton into a colourful disco party. I was trying to create a white "Hurt Flash" effect, using Material Blocks etc but noticed that the Tint doesn't colour correctly.
I was expecting a fully black color to not do anything, while a white color makes the character fully white.
Edit: Using latest versions of Unity 2023.1.9f1, and spine-unity-4.1-2023-08-21
Edit 2: Noticed there's "Overlay Color" if I enable "Color Adjustment", will try to use that for hurt flashes instead. Let me know if it's a bad idea...