Edges become sharp after flip normal I import a model from binary data and figure out that its normal vectors are in wrong direction. After flipping vectors, the faces do not look smooth like before although I try to use "Shading/Smooth faces" and "Clear sharps" feature. How could I do to make the face look smooth in this case? I attached the .blend file here. Thanks.
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Before flipping normals


After flipping normals
Your mesh has 211 double vertices that mess up the shading.

Select all vertices (Ctrl+A), disable Autosmooth and go:


Mesh > Clean up > Merge by distance (this will merge 211 double vertices)
Mesh > Normals > Recalculate outside
RMB > Shade Smooth


This will ensure you have a clean mesh, normals pointing out and proper shading.