Why does Netflix dominate Train to Busan streaming access?

A Netflix-related update says Netflix “lost” a near-perfect 95% RT horror title, but it’s now free to watch. The film is identified as Train to Busan, and the excerpt frames its availability shift as the reason the story is worth noting.

However, the excerpt doesn’t specify why Netflix lost the title in the first place (rights, licensing, or windowing) or what exact change made it “free to watch,” so those causes can’t be determined from the provided text.