The water-binding agents in gluten-free flour are more sensitive. If the dough is worked too hard, they will tear and release the water. This water can no longer be bound properly and will lead to a dough that is sticky - because unprocessed cold starch does not bind water.
A gluten-free dough that is sticky and too soft can be caused by the following reasons: you may have kneaded the dough too hard or too long, or you may have measured the wrong quantity of liquid.