I've mentioned this before as you made this mistake in Rise of Prussia too, but seems you've made it again. Lodz is a city in your game and quite an important one - the second biggest if I am correct. The problem is that during this timeframe it was a small village of 400 inhabitants. I suggest to scrap Lodz at all from the map and if balance needs that, to make Krakow and Poznan larger.
Here is the map of the Duchy of Warsaw if you need it!
