Replication with Repmgr + native streaming replication I have an environment where the old DBA used the repmgr. And now I need to add a second replica to use as a "dump server".

But my question is regarding using the native mode of PostgreSQL via stream replication. When I perform base_backup and a second replica is added, can it cause any side effects on repmgr?

I've never used repmgr in prod and I just want to make sure that a simple replica can ruin the whole cluster.
As per my experience, NO. it does not affect on repmgr.

i never tested on Production server. So please be careful when applying on Prodn server.