[{"_id":"17tegruebfjt73efdci342132","name":"Test User1","obj":"health=8,type=warrior"},{"_id":"wefewfefh32j3h42kvci342132","name":"Test User2","obj":"health=6,type=magician"},{"_id":"17tegruebfjt73efdci342133","name":"Test User1","obj":"type=warrior,health=9"},]

db.collection.aggregate([{$addFields:{objTransform:{$map:{input:{$split:["$obj",","]},in:{$split:["$$this","="]}}}}},{$match:{objTransform:{$elemMatch:{"0":"health","1":{$gt:"8"}}}}},{$unset:"objTransform"}])