The database upgrade that restored peace of mind - one user’s move from MySQL to MariaDB

Remember FOSDEM, three months ago? In a potentially dramatic move, German MySQL Server user Cantamen GmbH (a car sharing provider) decided to upgrade their MySQL 5.7 site with over 1 billion SQL queries a day, to MariaDB 10.11. The potential drama was because of the ambition doing it live on the production site, during the presentation at FOSDEM.
As described in several videos (one by MariaDB Foundation, one by Dirk Hillbrecht of Cantamen), it went well.
But what’s the take now? Three months have passed. Were there hiccups later on, or did everything run smoothly?
We decided to follow up. Does Dirk (still) have peace of mind?