My cropped top has the skin looking like a shirt please help

Hi. This is not a correct way of doing it.
When you exported a blend file, it was made of multiple meshgroups. You joined them into one, edited, imported back. Only one of them was replaced while other stayed.
The stomach area is a part of your garment. When you delete that area of the hoodie, you needed to replace it with a nude stomach.

- clone ymTop_EP03Hoodie again, export the blend, open it;
- the area you need to edit belongs to the same meshgroup, theres no need in joining all of them;
- select the meshgroup that contains the area you want to delete, switch to edit mode, in uv editor enable sync;
- select all uvs with A, assign your diffuse as the background;
- select these uvs, in 3d view press Delete, choose Faces;

- expand the rig, make top selectable, select it, in 3d view press Shift D, then Esc to duplicate;

- select top.001, in edit mode select all visible areas of the body, invert the selection, delete;

- select each uv and move it so that it does not overlap with the jacket's texture;

- in this order: select top.001, then in 3d view shift-select the hoodie, join with ctrl J;
- press B, select these 4 vertices on the hoodie, then hold Shift and select them on the body, Edges - Bridge edges;
- switch to edge select, select the same edge loops again, Mesh - Split - Faces by edges;
- select uvs of the neck and hands, Mesh - Merge - By distance;

- save, import back, edit the texture

it is called remove doubles

You do not need to rebake textures, you need to open the original textures in the image editing program and cut out the part of the hoodie that you removed. Export uv layout and use it as a guide

I'm so sorry, I think this might be the last thing I need help with
the belly shows the waistline of the boxers

package:
www.dropbox.com/scl/fi/ih5650ya5fc0kf4szim4u/hoodie.package?rlkey=jmcnod5zecoul1xgbqjo87lci&dl=0

Blender:
www.dropbox.com/scl/fi/y82sjkgkxzyxo3qrxmhib/step-5.blend?rlkey=5d0se6cf24k66ek0qj4evk6ea&dl=0

Texture:
www.dropbox.com/scl/fi/0immf531xce9wl3qnf5ba/og.png?rlkey=hjfoewy41av3hdgdbhn6bltdc&dl=0