Products woven from raw cotton fiber are prone to shrinking by up to 20%.
Even pre-washed garments behave this way. Cotton fibers have little elasticity, so it is advisable not to use a dryer and instead air dry to counteract this natural effect on the fiber and fabric.
The more you use them, the less the shrinkage effect will be between each use and wash, significantly improving their absorbent capacity. Wash separately to avoid lint traces on other garments.