Good catch Erwin!

Although WordPress and most browsers support AVIF files, Google Search actually doesn’t support it (at least not yet). That means AVIF images can’t be indexed, can’t appear in Google Image Search, and Google won’t even analyze and index a video if the thumbnail is in AVIF format.

As you can imagine, all of that is bad for SEO. So for now, we recommend sticking to more widely supported formats when it comes to web images, but I’ll be sure to update the article if/when Google does start supporting AVIF. 🙂