Shrinked window

Usually, when renovating or remodeling and it comes to windows you would tend to enlarge a window, if possible. In our case, the window of the smalest toilet (the one that hangs on the outside), was large enough - before the renovation.

But look what happened with the new window (before, during and after) :

It shrinked !
Somehow it is less than half of the before size.
However it has a very bold frame.