Hi, I'm trying to rig a figure. This is about my fourth time doing this. In the past, automatic weights has done a pretty good job with a problem here and there. On this figure, it's terrible. The vertex groups for middle finger, thumb, forearm and many others all manage to include a big chunk of the torso.
Lots of places online suggest checking normals, I've made sure that there are no inside normals facing out. Do you have any other suggestions as to what could make automatic weights go so wrong?
A couple things that have given me trouble with automatic weights is have verts stacked on top of each other. Go into edit mode select the entire mesh and "merge by distance" to clean anything up.
Making sure you don't have any random holes in the middle of your mesh as those can have unpredictable results. Holes with supporting geometry in my experience work fine but if you have a random rip between edges could create that error. ("merge by distance" may fix these areas as well.)
If you're still having issues, maybe try posting some pictures of what you're working with and we can try to help trouble shoot it.