I'm sorry for the inconvenience. Try toggling fullscreen manually by pressing ALT+ENTER as a workaround. I hope you enjoy the rest of the game!
Reinstalling did resolve the issue. But, I think the actual issue was that saving the game after changing the auto-fullscreen setting caused it to bug out: If that's a problem that can be patched out, great! Also, since I reinstalled the game from the itch.io desktop app, now whenever I click on "check for update", there's no acknowledgement that an update check was made. I think that has more to do with the app itself than the game's installation. So, I'll try as clean a reinstall as possible to see if that resolves this newfound issue. UPDATE: I can't uninstall the game from the itch.io desktop app. So if any updates come in, I might not receive them. Sorry if I'm causing so many problems for you.