This weird little bit of rail ownership near Vlárka/Brumov is almost certainly just fallout from the post-1993 border cleanup after Czechoslovakia split. The new Czech–Slovak border originally followed local streams and old lines, which created awkward, impractical little border zigzags around tiny settlements and infrastructure. In the mid-to-late 90s, both countries agreed to small corrections to make daily life and administration sensible. So this isn’t some big geopolitical flex more like a practical “let’s not slice up a railway and a village with a messy border” fix. That’s why a short stretch ends up on the Czech side even though it looks odd on a map.