Newer versions of MariaDB, such as this one included with Ubuntu 24.04:
Server version: 10.11.8-MariaDB-0ubuntu0.24.04.1 Ubuntu 24.04
change the default behavior to not automatically set timestamp defaults and on update values:
$ mysqld --verbose --help | grep explicit-defaults-for-timestamp
explicit-defaults-for-timestamp TRUE
whereas my older machines allowed it:
$ mysqld --verbose --help | grep explicit-defaults-for-timestamp
explicit-defaults-for-timestamp FALSE
More background on the flag here:
https://dev.mysql.com/doc/refman/8.4/en/timestamp-initialization.html