Database
[{"Timeline":"2021-W01","Sales":10,"Country":"A"},{"Timeline":"2021-W02","Sales":11,"Country":"A"},{"Timeline":"2021-W03","Sales":12,"Country":"A"},{"Timeline":"2021-W04","Sales":13,"Country":"A"}]
Query
db.collection.aggregate([{$set:{Time:{$toInt:{$dateToString:{date:{$dateFromString:{dateString:"$Timeline",format:"%G-W%V"}},format:"%G%V"}}}}},{$bucket:{groupBy:"$Time",boundaries:[202101,202103,202105],default:"Other",output:{totalSales:{$sum:"$Sales"},start:{$min:"$Time"},end:{$max:"$Time"},}}}])