You may only pay $350 or $100 in cash, but the homeowner grant fully belongs to and is credited to you. Legally, you’re paying your taxes in full. Someone telling you that you are only paying a small amount is both belittling and disingenuous.
Whether the grant comes from the drug dealer down the road, a rich uncle, or the provincial government by way of a government grant is immaterial. It is credited completely to you the homeowner. It is your money and by way of it you pay your taxes in full.