Currently, there is no sorting in `get_next_adhoc_task()` method:

https://github.com/moodle/moodle/blob/2c0b08c5a7e8c682f0621abb74a5eaf3817b0114/lib/classes/task/manager.php#L562-L564

Therefore, database engine returns unsorted set of records and under some circumstances records with more recent `nextruntime` can go ahead of records with later `nextruntime`.

In scenario when we are catching up with some ad-hoc tasks we want the latest tasks to be processed first.

To guarantee this we should add explicit sorting by `nextruntime`.