You misunderstood me. It may not be strictly required for sites to use JS to build these warnings. But in practice, today, that's how it works on sites that display them. And it definitely requires the user to have JS enabled to pass these obnoxious pop-ups.

JS is also used for things that are doable with CSS or even HTML only. This isn't the first time.

My tin-foil hat persona suspects it's yet another way to force me to disable the various script and ad-blockers in the guise of protecting users for privacy concerns. But my more realistic side assumes this is just laziness.