Vent stack

Just checked out this house and there’s no typical vent stack extending up past the roof line. Before I called this out, I wanted to consult with some people that are smarter than me. The pictures below show the only stacks that I can find and obviously none of them go above the roof. Any loopholes that I’m not aware of that make this ok? There is an AAV visible in the 3rd pic in case it goes unnoticed.

The code book I have says vents must be connected to open air through the roof, I do not see exceptions, reading between the lines I am guessing that the roof rule is there to prevent “frost closure” and to prevent sewer gas from entering an open window as per your pic.