Issue:
When importing a character into Unity, the mesh in the chest/armpit area becomes visibly deformed. The deformation looks like pinching or collapsing triangles and incorrect shading, especially noticeable during animation or certain poses.

Steps to reproduce:
1. Import a character created in Character Creator 5 into Unity.
2. Apply the default CC5 Unity setup (standard pipeline).
3. Play any animation or rotate the character to expose the chest/armpit area.
4. Observe the mesh deformation.

Actual Result:
The chest/armpit area mesh deforms incorrectly. The topology appears compressed, with visible artifacts and shading issues.

Expected Result:
The chest mesh should preserve correct shape and smooth deformation without collapsing or visible artifacts.

Additional Information:
- We tested the issue not only with our custom character, but also with the standard CC5 default model, and the problem is still present.
- This suggests the issue is likely not related to custom topology or skinning, but may be related to the CC5 to Unity pipeline, skin weights, or import/setup settings.
- Screenshots are attached for reference.