On some models that I upload, some vertices are randomly shifted. It’s not a triangulation problem. If I open the same (uploaded to sketchfab) file in Marmoset Toolbag or another sofrware (reimport it in Blender or 3ds Max), this problem does not exist.
I usually upload .fbx, but I also tried collada - the result is the same. I create files from 3ds Max and Blender - the result is again similar.
I didn’t notice this problem on static meshes, only on skeleton meshes.
I use Firefox browser and Windows 10.
Example
How to avoid the appearance of such artifacts?