The YouTube shortcode template has a very useful option for adding loading="lazy" (https://gohugo.io/shortcodes/youtube/#loading) to the iframe.

I use this a lot, it's very helpful if you have a YouTube embed at the bottom of the page so it doesn't automatically begin downloading a lot of CSS/JS from youtube.com on page load improving performance and saving resources.

I'd really like to see this option also be added to the Vimeo shortcode too! Especially as Vimeo loads a LOT of JavaScript for its embeds.
https://gohugo.io/shortcodes/vimeo/