Unfortunately, as you say, it's very easy to freeze a GPU if you start doing more complex SVGs.
But the effect, due to the way it's produced, is more like a hot air distortion, only without the faint shimmering. It's completely raster in nature, AFAICT, and is likely implemented as a GPU shader (which is good from the performance POV).
An effect more like an unsteady human hand could likely be achieved by oscillating nodes in the direction perpendicular to the curvature, and adding some random jitter to the control points.
I used rive.app to encode the frames and create a state machine to move between the states. Perhaps I can simplify this even more.
> /? svg animation: https://hn.algolia.com/?dateRange=all&page=0&prefix=false&qu...
It's a very distinct style.
