Popular misconceptions abound about “the floating island of trash” that supposedly exists in the center of the Pacific Ocean. It’s not true. Plastic breaks down in sunlight and ocean currents, and there is no huge mass of plastic floating in the center of the Pacific Ocean. If there were, then Hawaii, which is pretty near the center of the Pacific Ocean, would not be as popular a vacation destination as it is. Here’s the link.
If your life jacket relies upon the watertightness of the pocket containing the flotation medium, and if that has been compromised, then I wouldn’t rely upon that life jacket at all, at any time. Think of which of your guests you’d like to sacrifice, and give that person the jacket, or keep it for your own use. Not comfortable with that idea? Then toss it (destroy it, so that no one else gets the idea that you’ve got hold of) and replace it. Best to replace it with a solid flotation medium, so that punctures don’t affect utility.
Happy sailing. Keep your guests alive, please.