Database

[{"title_number":"46345734","status":"applied","updated":"02/04/2022","rev_num":1,"revs":[{"title_number":"46345734","status":"unapplied","updated":"02/06/2022","rev_num":2}]},{"title_number":"46345802","status":"unapplied","updated":"02/05/2022","rev_num":1,"revs":[{"title_number":"46345802","status":"applied","updated":"02/05/2022","rev_num":2},{"title_number":"46345802","status":"applied","updated":"02/06/2022","rev_num":3}]}]

Query

db.collection.aggregate([{"$addFields":{"revs":{$filter:{input:"$revs",as:"rev",cond:{$eq:["$$rev.status","applied"]}}}}},{$group:{_id:null,applied_doc:{$push:{$cond:[{$eq:["$status","applied"]},{_id:"_id",title_number:"$title_number",status:"$status",updated:"$updated",rev_num:"$rev_num",revs:"$revs"},"$$REMOVE"]}},applied_sub_doc:{$push:"$revs"}},},{$set:{applied_sub_doc:{$reduce:{input:"$applied_sub_doc",initialValue:[],in:{$concatArrays:["$$value","$$this"],},},},},},{$project:{mixedDocs:{$concatArrays:["$applied_doc","$applied_sub_doc"],},},},{$unwind:"$mixedDocs",},{$replaceWith:"$mixedDocs",},])

Result