Hard case suit cases are usually 20 pounds heavier than a fabric or cloth style luggage.

Cotton is a very lightweight plant, and fabric. Metal is much heavier than cotton.

You can use crayons on just about any kind of fabric. For some of the synthetics, you would find it easier to use a frame, or hoop to hold it tight. The best fabric is heavier cotton, denim, or canvas.

If you are working with a special project, you should purchase the Fabric Crayons, which are specially formulated to write on fabric.

The jumper probabaly retained water in the fabric and all the extra water makes it heavier. Once it dries it should feel the same.

Imagine having two heavy balls of the same weight and size on a rubbery fabric. If you increase the size of one, that will bend the fabric so that the smaller will move towards the larger.
What you are seeing is that the heavier "attracts" the lighter. We call this gravity.