Please find the extracts from mongodb doc,
1)
Sharded Clusters
mongodump and mongorestore cannot be part of a backup strategy for 4.2+ sharded clusters that have sharded transactions in progress, as backups created with mongodump do not maintain the atomicity guarantees of transactions across shards.
2)Lock the Cluster
The sharded cluster must remain locked during the backup process to protect the database from writes, which may cause inconsistencies in the backup.
So above two itself suggests we cannot use mongodump for backups(production).
Is it possible to create application using wiredtiger for performing hot online backups?
https://source.wiredtiger.com/11.2.0/command_line.html#util_backup