SERVER-60466, a mongod started with --shardsvr but does not yet have a shard identity would temporarily use the replica set version of the LogicalTimeValidator, which would later get replaced by sharded version of the LogicalTimeValidator during sharding initialization. The LogicalTimeValidator is a unique pointer decoration on the ServiceContext. As a result, once the replica set LogicalTimeValidator is replaced by the sharded replica set. The replica set LogicalTimeValidator object would become invalid and could lead to segmentation fault as seen in BF-29030. One resolution would be to make the LogicalTimeValidator a shared_ptr decoration so threads that have the replica set LogicalTimeValidator while sharding initialization occurs can continue to use it until they are done.