> When removing the animation (tip: remove the css or set status to “paused”), the CPU sits near 0% and the GPU near 0%.
Seems pretty easy to replicate. I don't know this particular screen they're talking about otherwise I would try it. I definitely have used CSS animations before without thinking about potential performance implications so this does seem like a good thing to try to understand in better detail.
I agree that rotating a square doesn't seem like it should be the root cause here though.
EDIT: I suppose it is possible that you are still correct though. Perhaps there is some JavaScript that is looking at the CSS properties as a way to trigger more significant work. It seems like a hacky thing to do, but it would be possible in principal.
