[{"_id":"123","item1":"group 1","item2":"abc","item3":"abc","date":"2022-01-01"},{"_id":"234","item1":"group 1","item2":"abc","item3":"abc","date":"2022-01-02"},{"_id":"345","item1":"group 1","item2":"abc","item3":"abc","date":"2022-01-02"},{"_id":"789","item1":"group 2","item2":"abc","item3":"abc","date":"2022-01-01"},{"_id":"678","item1":"group 2","item2":"abc","item3":"abc","date":"2022-01-02"},{"_id":"456","item1":"group 2","item2":"abc","item3":"abc","date":"2022-01-02"}]

db.collection.aggregate([{$group:{"_id":"$item1","max_date":{$max:"$date"},"records":{$push:"$$ROOT"}}},{"$project":{items:{"$filter":{"input":"$records","as":"records","cond":{$eq:["$$records.date","$max_date"]}}}}},{$replaceRoot:{newRoot:{results:"$items"}}}])