Neither the official modelviewer.dev website, nor our own pages seem to handle <model-viewer> properly on iPadOS 17.0 No 3D content is shown and no background styling is performed.
I tested the same on iPhoneOS 17.0 without problems.
Created attachment 467750 [details] Screenshot of Google's official modelviewer.dev website showing no 3D content
Also filed as FB13187835
rdar://115722249
model-viewer team is informed https://github.com/google/model-viewer/issues/4468
model-viewer team (elalish, Emmett Lalish) said, Apple needs to fix this.
This seems to affect all ThreeJS based projects.
iPadOS 17.0.1 seems to fix that