Register Embed For Padlet

I’ve been asked by education clients for an easy to embed Padlet.com content from a content URL (w/o copying HTMLembed code). I notice on the Padlet.com site that it says this is supported on WordPress.com but not self-hosted.

Yes it works there
https://cogdogblog.wordpress.com/2020/02/28/padlets-embed-here/

Why are more sites supported for embeds on WP.com than WP.org? Why do I not get the WP.com support with JetPack plugin?

I’m trying to write my own wp_embed_register_handler code and it keeps failing:

add_action( 'init', 'wp_register_padlet_embed');

function wp_register_padlet_embed(){
	$regex_url = '#https?://padlet\.com/([a-zA-Z0-9_-]+)/([a-zA-Z0-9_-]+)$#i';

	wp_embed_register_handler(
			'padlet',
			$regex_url,
			'wp_embed_handler_padlet'
	);

}

function wp_embed_handler_padlet( $matches, $attr, $url, $rawattr ) {

	$embed = sprintf(
		'<div class="padlet-embed"><iframe src="//padlet.com/embed/%1$s" frameborder="0" allow="camera;microphone;geolocation"></iframe></div>',
		esc_attr($matches[2])
	);

	return apply_filters( 'embed_padlet', $embed, $matches, $attr, $url, $rawattr );
}

But I keep getting fail to embed errors. There’s not much I can see to debug this, I am thinking it’s my weak regex skills, but this function is really poorly documented (the examples are outdated)

I’d be happy to see wp_embed_register_handler code used on WP>com I can compare to my own that is not working.