The list of multikey updates is batched and keyed by collection name during oplog application OplogApplierImpl::_applyOplogBatch. In a recovery scenario where there may be multiple collections with the same name at different points in history, this mapping could be problematic. Downstream components such as the replication StorageInterface::setIndexIsMultikey() would be less prone to looking up the wrong collection from the collection catalog if given the collection UUID.

A more robust way to maintain the multikey information to update would be to use the collection UUID rather than the namespace.