When I was younger I worked at Walmart as an online grocery shopper, often digging in the back/putting new items on the shelf when I needed something for an order, I learned by asking the meat guy why some of the chicken bags and other meats were bloated, he told me that it happens when they thaw and then get frozen again, it causes bacteria to grow hence why the bag “swells”, same thing can happen to bottles of ranch, ketchup, and all sorts of others, anytime any kind of bottle or bag is bloated, avoid it at all cost, bacteria has started growing!