Hello Mircea!
How are you?
This behavior is expected in MySQL Group Replication and is not a configuration or version issue.
When Group Replication is active, the read_only and super_read_only variables are automatically managed by the plugin, even after restarting mysqld.
Therefore, any value defined in /etc/my.cnf, SET GLOBAL, or SET PERSIST is ignored.
Even in multi-primary mode, Group Replication keeps these variables ON by design, using internal controls to allow writing to nodes that are enabled.
That is, a node can accept writing normally even with `super_read_only=ON`.
I recommend checking below:
“If READ_ONLY is the exit action, the instance switches MySQL to super read only mode by setting the system variable super_read_only to ON.”
https://dev.mysql.com/doc/refman/8.4/en/group-replication-responses-failure-exit.html
“If super_read_only=ON is set and the member should join as a primary, super_read_only is set to OFF once Group Replication successfully starts.”
https://dev.mysql.com/doc/refman/8.4/en/start-group-replication.html