Thank you for the workaround: it worked. I really hope you find the source of the fullscreen bug. When I made that post, though, it was after the new update was released, so maybe a fullscreen setting bug happened. I'll reinstall the game to see if that'll resolve anything.
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.