BUG #16873: CREATE SUBSCRIPTION command hangs (Cross version logical replication) Wait event LibPQWalReceiverRec

The following bug has been logged on the website:

Bug reference:      16873
Logged by:          Andriy Bartash
Email address:      abartash@xmatters.com
PostgreSQL version: 13.2
Operating system:   CentOS7
Description:

Hello
Establishing logical replication between PG12 and PG13.2 and CREATE
SUBSCRIPTION command hangs.
Query bellow shows exact command, how long it's been running and wait
event.
Source and target PG clusters are running on different VMs
SELECT query, xact_start, now(),wait_event FROM pg_stat_activity where query
like 'CREATE SUBSCRIPTION%';
                                                        query
                                        |          xact_start           |
          now              |       wait_event

---------------------------------------------------------------------------------------------------------------------+-------------------------------+-------------------------------+-------------------------
 CREATE SUBSCRIPTION "auditstore_subscription"
                                       +| 2021-02-18 23:07:23.814108+00 |
2021-02-19 00:16:37.237905+00 | LibPQWalReceiverReceive
             CONNECTION 'host=10.141.0.29 port=5432
user=auditstore_publisher password=<PWD> dbname=auditstore'+|
               |                               |
             PUBLICATION "auditstore_publication";
                                        |                               |
                           |
(1 row)