Why does wearing the clothes will change the color of body

Hi. We would need to see your package file to know for sure. My guess is that you saved dds files with incorrect settings. Must be dxt5 (or bc3 in newer versions) with generated mipmaps. Most likely culprit is your normal map (but diffuse can do is as well)

It has to be completely re-done. Issues:
- a shadow map made incorrectly. Only places where the garments casts shadows must be gray. This is the main cause of the problem you're addressing;
- must not move uvs of the body. The second cause;
- must not subdivide the body;
- if making a dress, all data must come from a dress of similar length;
- vertex painted with wrong colors;
- uvs in uv_0 must not be scaled individually unless difference in quality is acceptable. It makes sense for buttons to be of better quality than the rest but the front must not be better than the back, you can see a stark difference:



- delete your current blend file;
- go back to MD and split both patterns in two in the waist area. You will be able to utilize available uv space better if there are 4 medium patterns instead of 2 huge;
- with all patterns selected, increase particle distance. Your garment doesnt have fine details, it does not need dense topology to preserve anything;
- export as thin and weld;
- clone a dress of similar length ( can be a bit longer but not shorter ), export the blend, open;
- follow this video in blender 4.2 until the end. This is a start-to-finish process, you do not need to do any extra steps. If what is shown in tutorials you saw previously contradicts what is shown here, forget about that