Hello,
I'm not part of the staff at Stadia--in fact, I'm just a player on Stadia, but I also did notice some input lag yesterday as well, but it was between 6:30 and 7 PM Eastern time. It only occurred when I was in the middle of a fight, but once I had stopped moving, the game would return to its normal state. I started experiencing the same thing you did after I rebooted my computer from crashing (This isn't important, but it might worth mentioning that I was playing Stadia at the same time it happened, and when I got back into the game, it resumed my spot, so I'm not sure if that had anything to do with it? It probably didn't).