In a <picture>, the first <source> has type="image/avif" and a media query that matches the current viewport, but the browser does not support AVIF. The second <source> is WebP (supported). Which image is chosen?
<picture>
<source srcset="a.avif" type="image/avif" media="(min-width: 600px)">
<source srcset="a.webp" type="image/webp">
<img src="a.jpg" alt="">
</picture>