[{_id:ObjectId("6255a889fb63822bd51b0356"),answers:{"6255a889fb63822bd51b0326":{value:ObjectId("6255a889fb63822bd51b0329"),},"6255a889fb63822bd51b032a":{value:[ObjectId("6255a889fb63822bd51b0321"),ObjectId("6255a889fb63822bd51b032d")],},"6255a889fb63822bd51b032e":{value:2,comment:"hello",}},createdAt:ISODate("2022-03-12T17:27:53.890Z")}]

db.collection.aggregate([{$project:{_id:0,answers:{"$map":{"input":{$objectToArray:"$answers"},"as":"a","in":{k:"$$a.k",v:"$$a.v.value"}}},date:{$dateToString:{format:"%Y-%m-%d",date:"$createdAt"}}}}])