It has often been noticed that differences along the historical borders exist in Poland. See for example this article.
Here’s another article discussing the differences, and interestingly claims that the difference between the election result in former Prussian and Russian parts of Poland is likely due to other factors.
Quick Q: is it a coincidence that the orange vote somewhat matches the territory once owned my Weimar Germany?
It has often been noticed that differences along the historical borders exist in Poland. See for example this article.
Here’s another article discussing the differences, and interestingly claims that the difference between the election result in former Prussian and Russian parts of Poland is likely due to other factors.