[{_id:"910",requests:{"100":{date:"10/06/2022 11:24:19",isProcessed:false},"123":{date:"10/06/2022 11:24:19",isProcessed:false}}},/** Document 2*/{_id:"743",requests:{"999":{date:"10/06/2022 11:24:19",isProcessed:false},"152":{date:"10/06/2022 11:24:19",isProcessed:false}}}]

db.collection.update({},[{"$addFields":{"requests":{"$objectToArray":"$requests"}}},{"$addFields":{"requests":{"$map":{"input":"$requests","as":"kv","in":{k:"$$kv.k",v:{"$mergeObjects":["$$kv.v",{"isProcessed":true}]}}}}}},{"$addFields":{"requests":{"$arrayToObject":"$requests"}}}],{multi:true})