I’m pretty sure it’s just see through because the author wanted to show the mc’s full face but still wanted to show the fact that he is looking for the murder hence why the knife is in front of his face. I feel like if the author wanted to show that he is in danger of dying from Geon-woo the knife would be pointed at him or against his neck. Wait omg now I am just straight up overthinking this shit because Geon-woo is also on the same side of the knife Lee Young is showing that he isn’t actually the murderer and is helping Lee Young look for the murder. (I’m lowkey just delusional)
spoilers maybe
i feel like that was the cover hinting that ml isn't really the murderer (aka the fake knife) and that's just mc's biased view (the eyes through the knife)
-> but again mc is also holding the knife so idk if that's hinting he's somehow related to the murder motive or just indicating that initially ml's view he's the murderer, holding the fake knife
again, the only person that looks like mc is the dead so unless he faked his death i doubt it's the murderer's reflection bc it looks tm like mc ╮( ̄▽ ̄)╭

SCREW THIS CLIFFHANGER AAAAA GIMME MORE (╯°Д °)╯╧╧
Also this might just be me overthinking but from the cover, you can see the mcs other eye through the knife the ML is holding. But metal knives aren't see through, doesn't that mean that the knife is reflecting another person who looks like the mc? (I am definitely high, or the knife is made of see through material. It's probably the former)
(▰˘◡˘▰)