As other have stated it’s from the result, when I came last year my test was almost 4 days old.
For simplicity at the airport I would suggest if it’s feasible to get the test and the results both done within 72 hours, last thing you want to deal with is a confused flight worker
i think until there’s a reasonable option for border runs they will keep the Covid extension, and as already announced not be so easy handing them out. If you’re on your 5+ one I would have a Plan B
there was someone a couple weeks ago who had a test and go booked but I think it was figured out there thai pass said sandbox not exemption and they were forced to book a 7 day, I can’t imagine how the airline could be so confused at this point. Best of luck