/dev/loop* are loop devices making plain files accessible as block devices. They have nothing to do with RAM occupation. They are typically used for mounting disk images, in your case apparently for Ubuntu Snap.

What is loop device Ubuntu?

The loop device is a block device that maps its data blocks not to a physical device such as a hard disk or optical disk drive, but to the blocks of a regular file in a filesystem or to another block device.

What is Loop disk in Linux?

In Unix-like operating systems, a loop device, vnd (vnode disk), or lofi (loop file interface) is a pseudo-device that makes a computer file accessible as a block device. … Thus, if the file contains an entire file system, the file may then be mounted as if it were a disk device.