Please check out my comment from another thread.
It does look pretty suspicious and may be glued. You should try weighing the pack, and also take a picture with a flashlight behind it shining through the crimp.
I do own a few packs which look like this and I believe were actual factory defects. The one part that looks strangest to me is the defect continues into the yellow ink area.
It is quite difficult to get the silver layer and clear plastic backing layer to separate as much as yours. Typically if you put a knife down the seam, or rip a pack you usually get a cleanish separation of the two separate silver layers and never see the clear layer.
The other interesting part I notice that could indicate it is a factory defect is that the vertical crimp lines on the back flap are off center and are partially on the artwork. Normally only the silver flap should have the crimp marks. There could have been some kind of misalignment with the crimping process that caused the defect.
If resealed, it would mean someone only partially ripped the corner only and then peeked inside and didn’t like what they found.
I am going to side more with it being a defect, but hard to be definitive.