The plugin-load option can be somewhat dangerous to use. The documentation says the following:
Special care must be taken when specifying the --plugin-load option multiple times, or when specifying both the --plugin-load option and the --plugin-load-add option together. The --plugin-load option resets the plugin load list, and this can cause unexpected problems if you are not aware. The --plugin-load-add option does not reset the plugin load list, so it is much safer to use.
This behavior can lead to confusing issues, especially when a user has multiple configuration files, and they aren't aware of the load order.
Currently, when MariaDB encounters the plugin-load option, it just frees the list without logging anything:
If log_warnings is set to some value (maybe 2?), and if the plugin-load list is non-empty, then I think it should log a warning like this: