World Scholar's Cup in Xiamen - What could possibly go wrong?

Back in December 2021, I qualified to the Global Round of the World Scholar's Cup. The Not-Quite Global was scheduled to be in Shanghai, then it was changed to Hangzhou for COVID reasons, and then it changed again to Chengdu, and then again to Xiamen.

So while my two teammates went on the high-speed rail on the day of registration, I went on the Tesla a day early to take a few pictures of the famous Fujian tulou (mud buildings), which happens to be a UNESCO world heritage site.
So the morning of registration, we got a message from a few other participating students that the globals were scheduled to be cancelled.
And the WSC team sent this Instagram post with a tag at the bottom:
But at noon, we called them and they said that everything was normal. Because of COVID, though, my teammates' train was delayed by a few hours.
Then, at 9 PM, they sent an email saying that it was cancelled because of COVID.
There were 7 new cases in Xiamen that day, and there was a concert going on in the other side of the city.
The 2 million residents of Xiamen Island are required to undergo nucleic acid testing overnight. If it is found that the spread has already begun, the entire island will be locked down for 14 days.