Mateusz Konieczny
https://www.openstreetmap.org/relation/6897966#map=16/49.5031/18.6741 - this is not supposed to be partially in Czech Republic, right?

Has Slovakia really created protected area covering part of Czech Republic?

What https://en.wikipedia.org/wiki/Kysuce_Protected_Landscape_Area mentions about area indicates that it ends on national border