Source

File: wp-includes/rest-api/endpoints/class-wp-rest-block-directory-controller.php

protected function prepare_links( $plugin ) {
		$links = array(
			'https://api.w.org/install-plugin' => array(
				'href' => add_query_arg( 'slug', urlencode( $plugin['slug'] ), rest_url( 'wp/v2/plugins' ) ),
			),
		);

		$plugin_file = $this->find_plugin_for_slug( $plugin['slug'] );

		if ( $plugin_file ) {
			$links['https://api.w.org/plugin'] = array(
				'href'       => rest_url( 'wp/v2/plugins/' . substr( $plugin_file, 0, - 4 ) ),
				'embeddable' => true,
			);
		}

		return $links;
	}