Update or include option for Mariadb 10.2.7
With the upcoming release of Drupal 9, scheduled for June 2020, please consider upgrading MariaDB from 10.1 to 10.2.7 or greater, or including this version as an option when creating a new database in Cloudsites.
Your installs are public-facing: any of your customers running your out-of-support version of MariaDB are wide-open to anything new which comes along from yesterday.
Phil W commented
From here: https://mariadb.com/kb/en/changes-improvements-in-mariadb-101/
"MariaDB 10.1 ... will be supported until October 2020."
It's actually October 17 2020. Twenty-one days from now.
So yeah, either withdraw the product, which will be by then no longer supported and therefore insecure, or upgrade it please. My vote is for t he second of those.