[{"_id":ObjectId("65aa4921c767f95a70b8867f"),"creator":"Henry","date":"2023-12-22","channels":[{"key":"HTV","value":1}]},{"_id":ObjectId("65aa4921c767f95a70b8867a"),"creator":"Max","date":"2023-12-23","channels":[{"key":"VTC","value":1}]},{"_id":ObjectId("65aa4921c767f95a70b88689"),"creator":"John","date":"2023-12-23","channels":[{"key":"VTC","value":2},{"key":"HTV","value":1}]}]

db.collection.aggregate([{$unwind:"$channels"},{$group:{_id:{date:"$date",key:"$channels.key"},value:{$sum:"$channels.value"}}},{$group:{_id:"$_id.date",channels:{$push:{key:"$_id.key",value:"$value"}},Total:{$sum:"$value"}}},{$set:{date:"$_id",_id:"$$REMOVE"}}])