Performance difference when executing multiple queries in 10.1 vs 10.3 and 10.4

I have a trivial PHP script using mysqli::multi_query (error handling ommited):

$queries = "...";
$db = new mysqli("localhost", $user, $pass, $database);
$db->multi_query($queries);
$db->close();

Here $queries refers to a large number (hundreds) of CREATE TABLE, ALTER TABLE and INSERT queries derived from a database migration system. I can provide them privately if needed.

When I run this script against MariaDB 10.1, it returns immediately, and a SHOW PROCESSLIST on the MariaDB console shows tables being created after the script has finished running. In other words, it's as if the queries run asynchronously.

If I upgrade to 10.3 or 10.4, the behavior changes and becomes "synchronous": the script takes minutes to run and only finishes once every query has run.

Is this a known behavior? Is there a configuration setting that can restore the behavior from 10.1?

I've tested this on an Ubuntu 18.04 VM with packages installed from MariaDB's APT repositories, using default configurations.