Just putting it out here as some people haven't figured this out yet. Manwha's use white backgrounds between their panels as transitions, so pay attention to whenever that changes to black. A black background transition between panels means you're witnessing a flashback. The whole epilogue chapters are flashbacks. And yes, it's common across 99% of all manwha's I've read, it's a very easy way for them to show you're reading a flashback without having to write that it as one. 😄