code: protected function getReplica()
      {
          if ($this->enableReplicas === false) {
              return $this->redis;
          }
  
          if ($this->_replica !== null) {
              return $this->_replica;
          }
  
          if (empty($this->replicas)) {
              return $this->_replica = $this->redis;
          }
  
          $replicas = $this->replicas;
          shuffle($replicas);
          $config = array_shift($replicas);
          $this->_replica = Instance::ensure($config, Connection::className());
          return $this->_replica;
      }
docs: It will return the current Replica Redis [[Connection]], and fall back to default [[redis]] [[Connection]]
  defined in this instance. Only used in getValue() and getValues().
  @since 2.0.8
  @return array|string|Connection
  @throws \yii\base\InvalidConfigException