Cutoff-mode setting

--cutoff-mode HARD|SOFT|CAUTIOUS              Mode to stop transfers when reaching the max transfer limit HARD|SOFT|CAUTIOUS (default HARD)

What does each of HARD|SOFT|CAUTIOUS actually do?

So I expect HARD terminates all transfers once the limit has been reached.

SOFT lets any current transfers finish, and not start any new ones.

What does CAUTIOUS do?

Stops transfer if next transfer would bring overall transfer volume over quota.

If interested about details have a look at PR which introduced it: