The dry powder in ABC fire extinguishers is non-toxic but can cause skin irritation. You can check the manufacturer’s website or the information on the extinguisher itself. The chemicals used vary by model and manufacturer but if they sprayed toxic chemicals they’d never be licensed for home use.
Try to minimize your exposure using a surgical mask or at least the kind sold for yard work or painting, but unless you have respiratory problems like asthma there shouldn’t be much risk if you have no mask.