They don’t go away on their own, every installed snap is mounted as its own loop device and snapd keeps an older revision or two so it can roll back, so the number moves around after updates. snap list --all shows which snaps they are, if one says disabled that’s the old revision and you can remove it with sudo snap remove <name> --revision=<rev>. about libation, if it’s installed as a snap itself that could be the actual problem, snaps are confined and can’t read folders outside your home or on other drives unless you connect the removable-media interface, so I’d check that before worrying about the loop devices.