This article explains the meaning of RV under the protocol column of the "show task replication" command output.

In some cases, when the show task replication command is run on Juniper devices, RV may show up as a new protocol.

show task replication
      Stateful Replication: Enabled
      RE mode: Master

  Protocol     Synchronization Status
  BGP                    Complete
  IS-IS                  Complete
  PIM                    Complete
  MPLS                  Complete
  RSVP                  Complete
  LDP                   Complete
  RV                    Complete

In this case, RV stands for "Route Validation." This is related to the Border Gateway Protocol (BGP) origin validation feature, where the routing device wants to match the route information (prefix, prefix length, and AS number) with an existing database to ensure that it is being learned on the device from the correct route originator. This database is populated on the device with information from a Resource Public Key Infra (RPKI) cache server, which in turn populates the information from the RPKI repository.

It is the primary Routing Engine that talks to the cache server to get the database, but in the event of a primary failover, the back-up RE needs to know this database as well, to have BGP origin validation feature function as expected. Which is why, the database is synchronized between the REs. After the database synchronization is complete, the status is available under show task replication output. Like other protocols, we should wait for synchronization to complete before performing the primary switchover.