Hello
Works for me.
Please share results of such queries:
select * from pg_stat_wal_receiver;
select * from pg_file_settings where name = 'primary_conninfo';
Cluster name will be used as fallback application name when no application_name was provided. I think you have several primary_conninfo, one of which is in postgresql.auto.conf that was created by pg_basebackup -R
regards, Sergei