According to Microsoft's Documentation, Azure should be configured to use SSL for connections.
In regards to default settings, they state the following:
By default, the database service should be configured to require SSL connections when connecting to MariaDB. We recommend to avoid disabling the SSL option whenever possible.
When provisioning a new Azure Database for MariaDB server through the Azure portal and CLI, enforcement of SSL connections is enabled by default.
Which ciphers are used by default? The documentation does not mention it.