Get the generated classname from a given block name.

function wp_get_block_default_classname( $block_name ) {
	// Generated HTML classes for blocks follow the `wp-block-{name}` nomenclature.
	// Blocks provided by WordPress drop the prefixes 'core/' or 'core-' (historically used in 'core-embed/').
	$classname = 'wp-block-' . preg_replace(
		'/^core-/',
		'',
		str_replace( '/', '-', $block_name )
	);

	/**
	 * Filters the default block className for server rendered blocks.
	 *
	 * @since 5.6.0
	 *
	 * @param string     $class_name The current applied classname.
	 * @param string     $block_name The block name.
	 */
	$classname = apply_filters( 'block_default_classname', $classname, $block_name );

	return $classname;
}