hit f11 notice many things:
the window frame reverts to os default for a split second
the graphics are not fitting to the screen right(which is why the cross hair is not right)
the screen jigles and jumps going into or out of f11.

On quit game button the windows frame shows again rather then 1.12.2 which doesn't do that.

Yes it relates to the crosshair but, I actually think this is a separate issue that the crosshair is being caused by non proper zoom for full screen and the graphics.