Database
[{"date_created":ISODate("2022-06-24T05:01:15.370Z"),"date_modified":ISODate("2022-06-29T05:01:15.370Z")},{"date_created":ISODate("2022-06-24T05:01:15.370Z"),"date_modified":ISODate("2022-06-19T05:01:15.370Z")},{"date_created":ISODate("2022-06-24T05:01:15.370Z")}]
Query
db.collection.find({$expr:{$or:[{$eq:[{$ifNull:["$date_modified",null]},null]},{$gt:["$date_modified","$date_created"]}]}})