What is the function of the list of loop devices? [duplicate]

The loop devices come from snap packages that you installed, one loop device for each snap package that is installed. If gnome-disk-utility package is installed, ISO images can be mounted as loop devices in Dolphin file manager's left pane under the Devices heading.

If you unmount the loop device of a snap package, the snap application will stop working until the next time you reboot or restart the computer, and then it will resume working normally. The right way to disable/enable a snap in the system is with the command sudo snap disable <name-of-snap-package> and enable a snap with sudo snap enable <name-of-snap-package>. The way to permanently delete a snap loop device is to uninstall the snap with the command sudo snap remove <name-of-snap-package>.