MySQL 8.4 Release Notes
A replication group uses a Group Replication communication protocol version that differs from the MySQL Server version of the members. To check the group's communication protocol version, issue the following statement on any member:
SELECT @@version, group_replication_get_communication_protocol();
+------------------------------------------------------------+
| @@version | group_replication_get_communication_protocol() |
+------------------------------------------------------------+
| 8.4.0 | 8.0.27 |
+------------------------------------------------------------+
As demonstrated, the MySQL 8.4 LTS series uses the
8.0.27
communication protocol.
For more information, see Section 20.5.1.4, “Setting a Group's Communication Protocol Version”.