Data race condition
The value of the shared data will be determined by the interleaving of thread execution. Thread shared data is accessed without holding an appropriate lock, possibly causing a race condition
/src/mongo/db/repl/shard_merge_recipient_service.cpp:1690: MISSING_LOCK 145067 Accessing "this->_oplogFetcherClient" without holding lock "mongo::repl::ShardMergeRecipientService::Instance._mutex". Elsewhere, "mongo::repl::ShardMergeRecipientService::Instance._oplogFetcherClient" is written to with "Instance._mutex" held 1 out of 1 times.