Re: HDR - not the same thing. HDR has been around for decades and every TV in every electronics store blasts you with HDR10 demos. It's well known. AV1 is extremely niche and deserves 2 words to describe it.
It's fine that you haven't heard of it before (you're one of today's lucky 10,000!) but it really isn't that niche. YouTube and Netflix (from TFA) also started switching to AV1 several years ago, so I would expect it to have similar name recognition to VP9 or WebM at this point. My only interaction with video codecs is having to futz around with ffmpeg to get stuff to play on my TV, and I heard about AV1 a year or two before it was published.
One word, or acronym, just isn't enough to describe anything on this modern world.
you might not know what AV1 is, and that's fine, but the headline doesn't need to contain all the background information it is possible to know about a topic. if you need clarification, click the link.