> When Lockdown Mode is enabled, your device won’t function like it typically does. (…)

> Web browsing - Certain complex web technologies are blocked, which might cause some websites to load more slowly or not operate correctly.

https://support.apple.com/en-us/105120

Most likely due to iOS lockdown mode disabling WebGL rendering.

Same for me on desktop Linux Chromium (with and without incognito mode), and yes console prints WebGL errors:

> scripts.js?v=1:3820 THREE.WebGLRenderer: A WebGL context could not be created. Reason: Web page caused context loss and was blocked

> scripts.js?v=1:3820 THREE.WebGLRenderer: A WebGL context could not be created. Reason: Failed to create a WebGL2 context.