I'm reporting a bug within the recent 0.18 "App Clip" release. It seems that AR experiences viewed within the App Clip draw layers in the reverse order than is expected when compared to the full app / desktop preview.
See the attached screenshots for examples of how it looks in the full app (Image 1) versus using the App Clip (Image 2). Hoping to get this bug squashed soon. Cheers. 🙂