[{"predictions":["611b85b9b2b924245526c125"],"_id":"611e40b6dd381f18cf63d15f","__v":0},{"predictions":["611b85b9b2b924245526c125"],"_id":"611e40b6dd381f18cf63d160","__v":0}]

db.collection.aggregate([{"$unwind":{"path":"$predictions"}},{"$group":{"_id":null,"predictions":{"$push":"$predictions"}}},{"$project":{"_id":0}}])