"Preparation for the partition of Poland", "Ukrainians forced". Where did the bilingual boards in Podlaskie come from

Photos of bilingual plaques with place names in Polish and Belarusian sparked a heated discussion online. There was no shortage of comments about the "Ukrainianization of Poland" and the threat of "partition." Meanwhile, the boards, which have been standing for years, are the consequence of laws protecting national and cultural minorities.