Please see https://blogs.perl.org/users/grinnz/2023/12/migrating-from-dbdmysql-to-dbdmariadb.html - while I think that it is a good idea for everyone to make the switch to DBD::MariaDB to avoid subtle and less-subtle issues, the switch can cause its own subtle bugs to code that was previously relying on DBD::mysql's broken unicode behavior. I'm not sure how it applies to Sqitch, but changing it for all db:mysql urls in arbitrary projects could introduce breaking changes.