- If it looks like dryer vent (location location location & size)
- & it smells like dryer vent (gets hot and wet when using the dryer)
- & quacks like dryer vent (you hear it, and its hot and wet, and it vibrates)
..... It is a dryer vent.
There are many posts on this forum and threads online where contractors have improperly used PVC for dryer vent. Just because PVC is used on high efficiency furnaces or water heaters does not make it safe for dryer use. It may not be PVC and most likely isn't.
The problem here is that the gasses the dryer produces are supposed to go through the pipe and then OUTSIDE. It is not safe for there to be holes or exit points for the exhaust INSIDE. While no one can say what levels are produced by your dryer, what can say is it will fluctuate. If the duct gets clogged, WHICH IT WILL! THEY ALL DO! (and this is why it is imperative you have it cleaned every 6-12 months or so on average; your mileage will vary), then the burn quality of the gas will be reduced, in addition, the clogged vent will force air wherever it can... Inside your home?
Next, the flexible ductwork - its best to have a rigid metal duct system in place but people use the flexible because its fast and simple. For short runs, its generally fine. If your run is long, it is not. If this system has a "T" unit in its line (it looks like it does) it really shouldn't, and this will "catch" lint as it blows past it. An odd plus here, is this gives you easy access to clean it out. (but its still a point gas can escape).
The one picture shows the dryer gas inlet as a straight 180 out of the dryer and they put the flexible gas line right to it, it (the dryer) is now pushed against the wall (by everyone that touches it), and the line is in danger of being kinked. This needs a 90 degree elbow to prevent this.
The dryer appears to be installed right where a beam in the wall is, so they went to the side quite a ways so there is now two bends, and the flexible duct may be getting compressed/squished in its compromised tight quarters.
They hacked the drywall and left it that way. Thus compromising the wall void. Completely avoidable. You can buy metal or plastic boxes to make this pretty and accessible:
Example website with pictures, (not promoting this company over any other)
This install was done poorly, sloppy, and wrong. You stated this is a new build house, I would have a home inspector, or family friend or relative take a walk through the home and make sure everything else is "right". They wont see everything, but they may find other issues you can get addressed under warranty perhaps.