There is a reason for this. The long-term strategy of Putin is to make his opponents weak by increasing internal tensions. These include weakening the European Union by forcing Lukashenka to deliver immigrants to EU borders and manipulating gas delivery, increasing racial tensions in the USA (in both camps), and in general increasing any kind of social conflict in countries Putin perceives as an enemy. In the case of Poland and Ukraine, Kremlin trolls concentrate a lot on the Volyn massacres, doing everything they can to rekindle enmity.