exact same issue with mine, began delaminating in late November and eventually the backing came away completely from the back, still attached but all bubbly and ripples…
decided i could live with it, until yesterday when my keyboard stopped working and nothing i could do could get it to reconnect and work…
not sure the two things are connected…. going to the store on monday… ipad and keyboard are 14 months old… but this feels like more than a regular warranty issue…