For people saying it's not working in any browser - do you have some kind of reduced motion preference setting turned on? I can imagine that would have an effect on something like this and it's definitely working in Chrome for me.
Enabling (layout.css.scroll-driven-animations.enabled) and refreshing the codepen gives a "we crashed this to prevent a crash from an infinite loop" clicking to allow the infinite loops allowed me to see the animation.
Fedora 44 Kernel: x86_64 Linux 7.0.10-201.fc44.x86_64 Firefox 151.0.2
The JS and bot check are for making additional functionality, beyond just showing the example, work easily. I.e. editing and sharing edits from a browser. If all you want is a static example, feel free to make it without these things.