Database
[{"hotelCode":2,"CreatedAt":new Date("2022-07-26T03:50:26Z"),"RateKey":1,},{"hotelCode":2,"CreatedAt":new Date("2022-07-26T03:51:26Z"),"RateKey":1,},{"hotelCode":2,"CreatedAt":new Date("2022-07-26T03:52:26Z"),"RateKey":1,},{"hotelCode":2,"CreatedAt":new Date("2022-07-26T03:54:26Z"),"RateKey":1,},{"hotelCode":4,"CreatedAt":new Date("2022-07-26T03:52:26Z"),"RateKey":5,},{"hotelCode":4,"CreatedAt":new Date("2022-07-26T03:55:26Z"),"RateKey":5,}]
Query
db.collection.aggregate([{$match:{}},{$sort:{CreatedAt:-1}},{$group:{_id:"$RateKey",hotel:{$first:"$$ROOT"}}},{"$replaceWith":"$hotel"}])