(Maybe it's a strobing artifact?)
I asked "please create a 3d animation", and pasted the Simon’s animation code.
I must admit I used a second prompt to adjust the opening camera angle, but that is all.
https://claude.ai/public/artifacts/b37a9ee2-f5bc-4ff9-ae90-a...
Firefox: No feet, no animation
Chrome: Feet included, animated very nicely (uses significant CPU)