I'm glad you enjoyed the game.
Yeah, the shader was a very last-minute addition, and it is really the first time I have attempted something like it. Apologies that I did not configure it properly for different resolutions. I imagine that while the UI elements are visible, they are most likely not scaled or positioned ideally on your 4K monitor either. This sort of just comes down to inexperience in that area, and I will pay more attention to this in the future.
Thank you for the feedback!