There are many reasons why we should use MariaDB; Not just performance.
The "egroupware"-container will use MariaDB by default for all installed tools. Even 'apt install MySQL-Client' will install MariaDB-Client instead and MySQL and MariaDB are not using the same auth mechs any longer. So switch to MariaDB on the DB-Server side will solve that issue.
There are many reasons why we should use MariaDB; Not just performance. The "egroupware"-container will use MariaDB by default for all installed tools. Even 'apt install MySQL-Client' will install MariaDB-Client instead and MySQL and MariaDB are not using the same auth mechs any longer. So switch to MariaDB on the DB-Server side will solve that issue.