We have some BFs that occur due to the problem of heartbeats not being able to be cancelled "fully" (any outstanding heartbeats that are sent across the network cannot be cancelled). TSERVER-36417 attempted to drop the pooled connection to removed nodes after a reconfig, but we saw the heartbeat issue prevent that ticket from being fixed.

As a workaround within the replication code, if a node sees a heartbeat from a removed node with the same version-term pair, we should not respond and continue to heartbeat. See linked tickets for context.