Water Heater Vent

Here’s a few pictures of a water heater vent, as you can see the vent from the water heater is combined with the vent from the furnace and is attached ahead of the furnace. The vent connector is also within 6 inches of combustibles, the insulation on the suction line and the csst gas line coating. I called this out and am being questioned because they had a permit signed off on the water heater install.