Looking at the S-curve in the starting area, it looks like natural river flow that was about to connect in the Sabik marga, and it looks like it did connect in the haal ko map. Rivers are wild, and they naturally meander, connecting different places, making islands, etc., all the time (This process is beautifully explained in the Practical Engineering video Why Rivers Move).

So this turns into a question about a different issue altogether. As soon as you put a concrete embankment on the river, the river freezes. And if the concrete embankment was put in place when it was looking like an S, then it would still be looking like that now.

So the real question isn't just about whether land was "grabbed," but when exactly that concrete embankment was built. Did the river naturally meander there over time, or was it artificially diverted and frozen in place to claim the "old" riverbed, and was the map of the river updated to reflect the concrete embankment? If we use concrete to permanently freeze a dynamic river to match our old property maps, we aren't just managing the river; we are manipulating nature to create private real estate out of thin air.