Ironically the videos on the page have jank as they load in it changes sizes
The intrinsicsize attribute was abandoned in favor of tweaking the way browsers handle the size attribute, iirc. These days it seems to just work if you give it the actual size there. aspect-ratio did make it and was added to CSS, yay. Very handy attribute.
The lack of that behavior was the most annoying part of responsive design for a while. I’m glad they figured out they could just use existing attributes, such (positive) changes of behavior happen very rarely on the web.