Hate to play armchair psychologist but I think Leno's lost interest in the project. He's not signing a new deal and he's not really been himself in the last 10 months or so.
It always felt wierd that we'd spend £20-25m on a back up keeper, in hindsight it should have been pretty bloody obvious that Arteta probably was going to put him in at the first available opportunity. Ironically it came off the back of a decent Leno shot stopping performance, but I think it was Arseblog who predicted he'd be dropped because he kept hitting it long.
On a sidenote, is it just a coincidence that we've seen our best football out the back either side of Leno being the number 1? Ramsdale hasn't exactly done anything amazing on the ball, it all seems pretty standard and he nearly messed up today, but it feels very natural. It was the same with Emi.