It's ok. We still read these. Just want to make sure other readers/forum users understand what the topic is about and can find what they need.
Yeah, unfortunately, this is the cost of it until Unity fixes the problem, if they consider it a problem at all.
But batching (and sorting) was ruined the moment your mesh had more than one submesh, really. So the Sorting Group is pretty harmless in that particular case.
Also notice how when your characters with multiple submeshes overlap each other, their parts also are also sandwiched. That's usually not what people want for separate skeletons.
Depending on your situation, you ideally either want to use runtime repacking (if multiple materials was because of equips), or making sure your Spine export only outputs one atlas page/image.
