If it’s GMB. then I bet the business is using the exact same address as another business. like a PO Box, Apartment Address, or a fake unit # that isnt registered with the postal service. That’s the most common reason. The biz owner likely doesn't want to use his real home address, but Google is actively going after businesses who attempt to be shady. The only way to clear the issue is to use a real address that isnt being used by another business. The last client I helped to get unsuspended it took 2 months to clear. Luckily that cleared before the virus came along. Good luck!