?

I'm pretty sure Gwonryeom was the person at the end of the chapter with the flower on his face since he's in his true form now and tends to distort his face from others. Plus he was lurking around the property before and the guardian spirit knew something was wrong with the house(this is just my guess take it with a grain of salt)

that or it's something Gwonryeom did to harm the MC since he's basically the bad guy now