It seems like the animation fbx exporter is broken. The mesh is exported just fine and can be imported in any application without issue. As soon as the animation is exported the mesh becomes broken when it is imported.
This has been reproduced in 4.19.2 (CL-4033788), 4.20 (CL-4212847), and Main 4.21 (CL-4221482)
Results: The shoulder and right hand are dislocated
Expected: The Skeleton/Mesh/Animation should be identical to the original one provided by the template
There's no existing public thread on this issue, so head over toAnswerHub just mention UE-61998 in the post.