[{"_id":ObjectId("61e3b88d3f14fb87161651c7"),"x":78,"y":157,"createdAt":"2022-09-21T10:11:40.479+00:00",},{"_id":ObjectId("61e3b88d3f14fb87161651c8"),"x":79,"y":158,"createdAt":"2022-09-21T15:11:45.479+00:00",},{"_id":ObjectId("61e3b88d3f14fb87161651c9"),"x":80,"y":159,"createdAt":"2022-09-23T15:11:45.479+00:00",},{"_id":ObjectId("61e3b88d3f14fb87161651c0"),"x":81,"y":160,"createdAt":"2022-08-21T15:11:45.479+00:00",},{"_id":ObjectId("61e3b88d3f14fb87161651c1"),"x":82,"y":161,"createdAt":"2021-07-22T15:11:45.479+00:00",},]

db.collection.aggregate([{$group:{_id:{$dateTrunc:{date:{"$dateFromString":{dateString:"$createdAt"}},unit:"week"}},count:{$sum:1}}}])