Previously if you used cscli decision add then the code would take some time before actually applying the ban on the MikroTik - by default up to 1h, which was not ideal :).
Now with setting UPDATE_ON_CSCLI=true (default) we detect if the incoming decisions are done with CrowdSec cscli, and thus the update is triggered immediately - in practice it takes about 5s of a delay due to the internal streaming update every 5s.
This helps to get bans quicker, for the price of a bit more no longer used address-lists, but with having DEFAULT_TTL_MAX set to 4h it should not be an issue - unless you have massive amount of blocked addresses, but in that case it is better to have MIKROTIK_UPDATE_FREQUENCY set to let say 5m.