UE5EA to Preview. Skeletal mesh reduced amount of polygons

I worked on a project in 5.0 EA2. All skeletal meshes looked fine. But when I moved to Preview, some skeletal meshes did broke. On images below we see normal skeletal mesh on the left, and mesh with reduced polygons on the right. The one on the left is not used anywhere in project, just imported it and did nothing. The one on the right is using as PlayerCharacter’s mesh.

I use Synty’s assets. Few packs. Some of them never used for now and all skeletal meshes inside these packs are ok. But those packs I use somehow (as weapon skeletal mesh, or vehicle, or character) appear to be broken.

How can it be fixed?

Tried to open Synty’s clean project. Same issue

Fugured out the solution. I exported skeletal mesh from Early Access project to Preview as FBX2020 and it looks good. So it happens the Preview works with newer FBX files?

Here I captured a video. On the left UE 5.0EA. On the right UE 5.0 Preview 1. I use default fbx file from Synty’s store which worked well on previous versions and import it into both UE project folders. In the EA version the mesh looks fine and in Preview its broken.