Some people confirmed/claimed they got rewards on last day of 7 day shinobi feast in previous editions. I wasn't online today after midnight server time, but usually events disappeared at wednesday/thursday midnight so there was no way to check who was the winner on the last day. I believe that winners in your screenshot are incorrect and date was just taken from your PC time.

What you posted is by no means proof, but that doesn't mean not announcing winners is right. Event should go one day into next event cicle with just the list of winners displayed and other options disabled.

Similar problem with wheel of fortune/sakura's gift, where last minute snipes exist... No way to check who sniped you if you weren't online and refreshing event page.