Rankmath description variable in Post to Google My Business plugin

pgmb_rank_math_seo.php

<?php

class PGMBRankMathSEOVariables implements \PGMB\Placeholders\VariableInterface {

	private $parent_id;

	public function __construct($parent_id) {
		$this->parent_id = $parent_id;
	}

	public function variables() {
		return [
			'%rank_math_description%'   => get_post_meta($this->parent_id, 'rank_math_description', true),
		];
	}
}

add_action('mbp_placeholder_decorators', function($decorators, $parent_post_id, $location){
	$rank_math_variables = new PGMBRankMathSEOVariables($parent_post_id);
	
	$decorators[] = $rank_math_variables;
	
	return $decorators;
	}
,10, 3);