Psychological / mental health thriller, recently on netflix maybe 3 or so years ago?

Hey,

Had a film i think i watched on netflix about 2-3 years ago…

Psychological kinda thriller about mental health - vague memories of the main character being a social recluse, potentially european / scandi film - lives in a pretty run down apartment area.

Travels to work on a bus, very grey/blue scenes with minimal talking, some internal dialogue maybe?

He ends up befriending / taking interest in a kid who’s playing outside the apartment in the kinda courtyard thing, lots of scenes of him looking down at the kid playing - maybe a scene of a balloon floating up?? Cant remember much else which is happening.

He ends up visiting hospital regularly, but twist at the end is that he is a patient in hospital or has developed some mental health issues?

Pls someone help, driving me crazy.