How to reproduce:
1. Download and import the attached unity package file named "UnityPackage_1268250"
2. Add the "Hair1" prefab into the Scene
3. Right-click on the object and Select Export to FBX
4. Set the Export Format -> Binary, Include -> Models Only and Object Position -> Absolute
5. Open the Exported fbx file on Blender

Expected result: Imported models looks the same as in Editor
Actual result: The exported mesh is mangled and does not look like the one in the Editor

Reproducible with: 2019.4.8f1, 2020.1.2f1, 2020.2.0a21
Could not test with: 2018.4.26f1(Model breaking in Editor once downgraded)

Reproducible with package versions: 2.0.1-preview.5, 2.0.3-preview.3, 3.2.0-preview.2

Notes:
1. Tested with Blender 2.83.4