What are you talking about?
The scale of the puzzle map is 1:1 with the adventure map and has always been so since version - minus one . pre pre pre ... pre alpha
but the piece is shown as 19x17, just like in the original. Select "show Dimension Door boundaries" in the quick menu and you can match the puzzle with the adventure map (and if you select "show grid," doing so becomes even easier).
Or do you want the puzzle map to show a piece of the same size as on the adventure map? I will never do that, because the larger the selected resolution, the easier it will be to identify the area. Select 4000x4000 (which is possible on any monitor in stretchable modes) and the entire map fits on the screen, so there's nothing left to search for.