@Vitali_Ladzisau I can’t see clearly here. Is the breakage point located at the UV seam? If so, it might be that a large displacement scale has caused the separation at the UV seam. Additionally, for models with Nanite enabled, it’s always recommended to use fully smoothed normals instead of hard normals, as this will result in completely different face reduction effects with Nanite. You can use the Nanite triangular Debug to view the differences. Also, when exporting the model from Maya, make sure to check the “Smoothing Groups” option.