I've actually had this issue for a while now. If I open Steam's in-game version, the 'hitbox' for any links, buttons, ect is shifted to the left. The effect worsens the to the right of the screen. The same also applies to the browser and other 'windows' openable from within the overlay.
Not sure if this is on DST's end or on Steam's end, but it doesn't happen with other Steam games.
Shift+Tab, hover over buttons.