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Switch from CAMERA FRONT to CAMERA BACK

From the Unity scene screenshot I can see that you have an object called "Fixed Character Camera"; is that an additional Camera that you use to render the character 3D model ?

If that's confirmed, you should be able to solve the issue by adding this simple script to your "Fixed Character Camera":

using UnityEngine;

public class BackfaceCulling : MonoBehaviour

{

  void OnPreRender() {

    GL.SetRevertBackfacing(false);

  }

}