Yes, the disc is supposed to move in a slightly random direction when you throw it. That's the concept behind the character being the "worst" at disc golf, because they can't even throw a straight shot and clear a simple course. I thought about trying to make that clearer in game with some sort of dialogue or further instruction, but I ended up opting not to do so. I'll see about updating the description though, because I can see how that could be unclear.
Thanks for checking out my game!