That seems to be the new overscroll feature zooming to wherever the cursor is pointed, not the center of the screen. But I agree that it could use some tuning. I've noticed that, for example, zooming out on a small image with Ctrl-0 tends to stick the image off in a corner, or even partly off-screen. It's also easy now to accidentally scroll the image halfway off-screen by getting too close to the edge with tools like Rectangle Select or Eraser.