It looks like a bug, so…
I just tried to upload a model packed into glTF bynary (.glb) and the mesh is a mess!
The same file was uploaded to an online glTF viewer (https://gltf-viewer.donmccurdy.com/) and there is no problem in its visualization.
Here is a picture from both view:
and here is the draft object I uploaded: https://sketchfab.com/3d-models/speaker-grasper-d-bh887-19f620069eec4dd294d53f2eec22f7d3
Thanks for any advice.