Fan power should be fed through a relay on the Ansel system to shut down the fans and make up air in case of fire suppression discharge.
You will certainly find fans that do not and may be grandfathered in before a code change or were not inspected. New hood installations must be permitted just like AC systems in my state. You will be turned down if there is no integrated relay.
I don't have a link to the code section to give you but it may vary from state to state.
As far as I know in Fla, all power is required to be removed from the hood except the exhaust fan ( i.e. lights, makeup fan, any receptacles under the hood ) during an Ansel trip. It has to be controlled through a relay panel. IMO.