Database
[{"_id":ObjectId("5eacfbe62758834aefdec003"),"UserId":"46942978-29f4-4521-9932-840cead6743e","Data":{"I":[{"k":"LRI39","v":[{"k":ISODate("2020-03-11T20:24:41.591Z"),"v":[{"k":ISODate("2020-03-11T20:24:41.594Z"),"v":{"Source":1,"Value":19}}]},{"k":ISODate("2020-01-22T11:37:23.393Z"),"v":[{"k":ISODate("2020-01-22T11:37:23.412Z"),"v":{"Source":1,"Value":20}}]}]}]}}]
Query
db.collection.aggregate([{$unwind:"$Data.I"},{$unwind:"$Data.I.v"},{$sort:{"Data.I.v.k":-1}},{$group:{_id:{_id:"$_id",key:"$Data.I.k"},document:{$first:"$$ROOT"}}},{$replaceRoot:{newRoot:"$document"}}])