I am just a bit confused. It says that the game jam ends in 16 hours but it also says that is ends at 12:00 AM. The 16 hours would mean that it ends at 12:00 PM. Does itch,io not tell you when it end relative to your time zone?
I do not have an answer to this
You could summit your game before 12:00AM and if it isn't closed after that, polish it some more and summit the update before 12:00PM
it should say on the jam page. at least, it does on the itch.io desktop app.