Sure. In Catholicism (the religion of 80%+ of Polish people), homosexual acts are a sin. They are, according to the Catechism, intrinsically disordered. The pride flag is a symbol of tolerance of these acts. By depicting the Virgin Mary, the most important woman in the entire Catholic faith, with a rainbow halo, they are depicting her as tolerant of homosexual acts. It is blasphemous. Ergo, it is hate speech (as ruled by the ECHR). You can say the ECHR doesn't matter but their rulings are legally binding in Poland whether you like it or not.