Can you confirm it forces ssl or forces ssl verification?
these are the changes
Comparing v3.3.10...v3.4.0 · mariadb-corporation/mariadb-connector-c
MariaDB Connector/C is used to connect applications developed in C/C++ to MariaDB and MySQL databases.The client library is LGPL licensed. - Comparing…
github.com
and this one is the force ssl verification.
Here are the ssl stuff from mariadb and there seems to be some require per user. Without seeing the logs I could not comment further. But is your connection running ssl (and just without the verify?) and it fails with the connector 3.4 (due to the verify) - the comments should be pretty useful in isolating this.
Securing Connections for Client and Server
Enabling TLS encryption in transit on both the client and server.
mariadb.com