If any blood gets on a flogger, from that moment it only gets used on that person.
Normal sweat and dirt, I would clean with a normal leather preparation and air.
Anti bac will destroy the leather over time, so if the flogger isn’t in constant use, use very sparingly.
Most non blood born infections do not live long outside the body.
If it is being used on multiple people regularly, then an anti bac must come into play followed by a conditioner.