db={"users":[{_id:ObjectId("63f3456fcdd8b763618809c1"),userName:"john",status:"created",updatedAt:ISODate("2023-02-21T10:29:08.032Z")},{_id:ObjectId("63f3456fcdd8b763618809c2"),userName:"john",status:"sent",updatedAt:ISODate("2023-02-21T10:30:16.456Z")},{_id:ObjectId("63f3456fcdd8b763618809c3"),userName:"john",status:"approved",updatedAt:ISODate("2023-02-21T10:30:29.157Z")},{_id:ObjectId("63f3456fcdd8b763618809e1"),userName:"ella",status:"created",updatedAt:ISODate("2023-02-14T07:52:48.45Z")},{_id:ObjectId("63f3456fcdd8b763618809e2"),userName:"ella",status:"sent",updatedAt:ISODate("2023-02-14T07:53:11.989Z")},]}

db.users.aggregate([{"$setWindowFields":{"partitionBy":"$userName","sortBy":{"updatedAt":-1},"output":{"rank":{"$rank":{}}}}},{$match:{rank:1}},{$unset:"rank"}])