Show replication status in Geo admin panel

I upgraded my Geo nodes from 8.16.x to a test 8.19 package. Somehow the replication from the secondary stopped working, but I wasn't aware. On the primary node, I did see a 401 error, which suggests the secondary didn't have the correct secret key:

On the secondary node, things looked fine:

gitlabhq_production=> select client_addr, state, sent_location, write_location,
gitlabhq_production->         flush_location, replay_location from pg_stat_replication;
 client_addr | state | sent_location | write_location | flush_location | replay_location 
-------------+-------+---------------+----------------+----------------+-----------------
(0 rows)

gitlabhq_production=> select now() - pg_last_xact_replay_timestamp() AS replication_delay;
 replication_delay 
-------------------
 
(1 row)