Looks like where the filter was plastic was cut. I've seen people do that to other vehicles and add a filter where there was no filter or prior opening.
I now know why the plastic was cut. Just went to change mine on my ‘07 Avalanche and it comes SEALED from the factory. I will have to get my dremel and actually cut a notch out like the previous owner did to this one. No other way!
It needs to be retrofitted once its been changed for the first time. I believe you can buy a plastic cover that holds it in place and screws into that vacant hole. Looks to me like whoever owned the vehicle before you had a rough time removing filter and ended up butchering it...
