ОК. Пробуйте так в процессоре web/catalog/products

ОК. Пробуйте так в процессоре web/catalog/products/getdata:

protected function setSelection(xPDOQuery $c) {
        $c = parent::setSelection($c); 

        .....................
        
        if($user_id = $this->modx->user->id){
            
            $OrdersTable = $this->modx->getTableName('Order');
            $OrderProductTable = $this->modx->getTableName('OrderProduct');
            
            $c->select(array(
                "(select count(*) FROM {$OrdersTable} o
                    INNER JOIN {$OrderProductTable} pt on o.id = pt.order_id
                    where 
                        pt.product_id = Product.id
                        AND o.contractor = {$user_id}
                ) as `exists`",
            ));
        }
        
        return $c;
    }