Steam Deck is an unsupported platform that we are not designing, testing or building the game for at this time. Once 1.0 releases we will decide which additional platforms we want to expand the game into.
Due to our Linux and controller support it does work fairly well.
This visual bug is brand new as of Wednesday and will be fixed.
Edit: I know this is too little too late because one of the replies to this got decimated over night but it's fine to have criticisms of the game everyone, please don't downvote people for raising their concerns. We need people to feel comfortable with saying the stuff they don't like, even if it's an unpopular opinion.