mysql – “mysqld” vs “server” in my.cnf

I used to see server-related configuration in my.cnf located under [mysqld].

However, I now come across configurations that use [server] instead.

It looks like both of them are synonyms, at least on MySQL 8.0, I can see that options under both groups apply to the MySQL server.

Is this a new feature of MySQL 8.0? Is one of them preferred over the other? Is one of them deprecated?