The opponent's planeswalker entered the battlefield with 10 loyalty counters & gained +2 on a +1 ability. Kaya the Inexorable.
same here with a Lilliana
It's vorinclex. He doubles the loyalty counter of planeswalkers that enter. He double all counters for his controller. I was really confused when it happened as well.
several planeswalkers seem to enter the battlefield with double loyalty when entering by means other than hard cast.