Ingame resolution can't be changed via the menu. Restart of the game doesn't help.
Always plays in native resolution.
This can only be done in Windowed or Fullscreen. Borderless will use fullscreen desktop resolution (typically native of your screen).
I am playing in fullscreen mode - but the resolution in the menu won't apply.
Edit: my mistake.
Why is Windowed (Borderless) default?
It is not anymore for new game installs since POB2 first patch if i'm not mistaken.
Game is installed since Alpha ¯_(ツ)_/¯