Mongodb aggregate $push with $cond and $each

Please try it without $each as below

Item.aggregate(
    [{
        $group: {
          _id: "$_id",
          numbers: {
            $push: {
              $cond: { 
                if: { $gt: [ "$price.percent", 70 ] }, 
                then: [10,25,50,70] ,
                else: null,
              }
            }
          }
        }
      }]);