This is decades old.
A man finds clues that somebody is living in his house. He finally hides in his house and, over time, sees people coming out of hiding.
Eventually he becomes the person who’s hiding in somebody else’s house without actually leaving his house. The change is very gradual.
this sounds like a conflation of El habitante incierto (The Uninvited Guest) (2004) and Bin-jip (3-Iron) (2004).