Model has weird mesh deformation need help

As the title says importing a fbx model and this weird deformation comes with import. It was at first crumpled together so I pull it’s vertices apart and made them de-crumpled however it still looks strange.

Model download -

You may delete the custom normals… but… IDK where you got this but the use of several armatures to modify some mesh according to some reference… is… unusual…
Edit:… no… in fact the mesh is …not good… there has to be several adjustments to be done… that’s in fact → modeling

The right side of the modeling has vertex damage.
Delete the right half and replicate the left half to restore it.

※ The other problem with the object is that

  1. Unconnected vertices
  2. Left/right out of symmetry