Do I need a hotel and PCR test if I am only transiting through Bangkok Airport?

A traveler flying from Cambodia to Bangkok for an onward flight without leaving the airport is uncertain about the necessity of booking a hotel for a PCR test on arrival. Comments suggest that if the traveler goes through immigration, they will need to apply for a Thailand Pass and book a hotel for day one PCR testing. However, if the airline checks their luggage through to the final destination, they may not need to pass immigration and can avoid these requirements.