@Sarah ****************
in that case I would check with the airline (TG?) to confirm. It sounds like you will be treated as a transit passenger and once you check-in in Singapore you will be checked all the way to Frankfurt - I think this means you will need to stay at BKK airport for the 10hr layover, and not be allowed to “cross the border” into Thailand (I’m just guessing here). If this is the case, I would do as others have suggested and buy a lounge access, or even a hotel room at the Novotel (a bit expensive though). Best of luck 😊