Originally Posted by NWIFlyer

QR will almost certainly have forwarded your passport number and personal details around 72 hours before your flight. The process, in normal times as well, is that the US analyses the API data the airlines send, and then sends an "okay to fly" notification back. The 72 hours is a US requirement to enable the analysis to take place in time.

The US would therefore have expected you to be on the flight, they would have determined you were trying to enter when not entitled, and their method of preventing you doing that was to cancel your ESTA.

You could have written to US CBP after your originally intended flight had landed, explaining the situation as by then they would know you didn't fly anyway. They might well have just restored your existing ESTA. Now you've re-applied it would probably be more sensible just to let it roll through the system - there's no reason to suppose it'll be refused.