db={"items":[{item_name:"exists1"},{item_name:"missing1"}],"items_recovery":[{item_name:"exists1"}]}

db.items.aggregate([{"$lookup":{"from":"items_recovery","localField":"item_name","foreignField":"item_name","pipeline":[{$limit:1}],"as":"items_recovery_lookup"}},{"$match":{items_recovery_lookup:[]}},{"$unset":"items_recovery_lookup"}])