Repairing an item repeatedly in anvil takes more levels the more you repair it.

The anvil takes more and more levels if you repair one tool. For example, if i repair elytra for the first time, it only takes 1 level per leather. The second time i try to repair it, it takes 2 levels per leather. The third time it's 4levels per leather. Is this supposed to work like that? because I haven't gotten help from support