Connector use utf8mb4 in all exchanges.
The problem is that current implementation use server truncated collation id in handshake packet. The problem is that when mariadb didn't have lots of collation, a single byte was ok. Since mysql8 and particulary for mariadb since MDEV-27009 that have huge amount of collation, relying on this value is not a good solution.

New implementation must execute "SET NAMES utf8mb4" ensuring that utf8mb4 will be the charset use in exchange, indicating to server to use correct collation.