Thanks for the details! It sounds like it might be a GPU driver issue. Could you let me know which graphics card you use, and if possible what version driver you're running? Seems like there's been reports of newer AMD drivers breaking Godot's 3D rendering so I'm curious if that might be the issue here. This game was made using Godot's forward+ renderer so if your driver has compatibility issues with Vulkan-based renderers then that might be an issue too.
Any additional info you can provide is greatly appreciated! Thanks again for taking the time to troubleshoot with me.