[{"_id":ObjectId("5f4e81f1da5ea3cb7c248a8f"),"type":"TYPE_1","updateTime":ISODate("2020-08-24T11:10:43.000Z")},{"_id":ObjectId("5f4e8206da5ea3cb7c248a90"),"type":"TYPE_1","updateTime":ISODate("2020-09-24T11:10:43.000Z")},{"_id":ObjectId("5f4e821fda5ea3cb7c248a91"),"type":"TYPE_2","updateTime":ISODate("2020-09-25T11:10:43.000Z")}]

db.collection.aggregate([{$group:{_id:"$type",count:{$sum:1},lastUpdate:{$max:"$updateTime"}}},{$group:{_id:null,types:{$push:{k:"$_id",v:"$count"}},lastUpdate:{$max:"$lastUpdate"}}},{$replaceWith:{$mergeObjects:[{lastUpdate:"$lastUpdate"},{$arrayToObject:"$types"}]}}])