TYSM! :)
Mmm yeah, that's not really a bug just a feature of how the buttons work. Built into Unity you can navigate the buttons by using arrow keys and activate them using various buttons. So you probably accidentally navigated to the quit button accidentally. There's probably a setting to turn this off but I'm not sure if I'm allowed to push changes I did after the jam ended. But I might update it after the voting period if people are still playing it by then. Thanks for trying it out :)