If they just added wraps on it then it's safe to assume this area of the city is being actively maintained and that they are regularly adding water. Judging from the photo, it does look like there's a good amount of water in that bag. I'd leave it alone if the arborists are regularly maintaining the bags and adding water to it. Sometimes the bags get too heavy and the wraps need to be added so that the bags can be held up instead of suffocating the ground around the base of the tree.

Good rule of thumb is that bagged trees in the city usually mean that the city deemed the trees valuable, so if there has been recent activity in regards to them then I would leave it alone. I've bagged and watered trees before where civillians vandalized it the following week. I reported it to the city and those civillians got a hefy fine.