[{"_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"}}},{$lookup:{from:"collection",let:{item1:"$_id",max_date:"$max_date"},pipeline:[{$match:{$expr:{$and:[{$eq:["$item1","$$item1"]},{$eq:["$date","$$max_date"]}]}}}],as:"items"}},{$match:{items:{$ne:[]}}},{$unwind:"$items"},{$replaceWith:"$items"}])