What are the new Test & Go rules for entering Thailand from December 24 onward?

From December 24 onward, travelers entering Thailand under the Test & Go program will still be required to stay only one night at a SHA+ hotel, as long as their Thailand Pass was approved before the cut-off. The new rules highlight the necessity of a second RT-PCR test on day 6 instead of an ATK antigen test. Clarifications suggest that confusion may arise from changes to protocols, but travelers who adhered to the previous rules should be unaffected except for the addition of the second test.