For arrival in Bangkok please put both your Test&Go hotel and after "quarantine" address in the arrival card. At minimum have it ready for immigration. When I passed through BKK on the 11th of March this delayed the queue a lot. I even had to scramble and repeat myself multiple times I was not heading to a hotel...
They also have some kind of new form where you have to fill in your details and what scheme you travel on. I forgot to take a photo but basically it is formulated quite badly like your have been determined to be suspected of covid. I assumed after checking it a few times it is more meant to be phrased that they don't know until test come back or you finish your sandbox or AQ.
TLDR : Answer Summary
When arriving in Bangkok under the Test & Go scheme, it's important to include both your Test & Go hotel and your address after quarantine on your arrival card. This information is crucial for immigration processing, and failure to have it prepared may cause delays. There is also a new form introduced that requires additional details, which some travelers have found confusing. Experiences with immigration officers may vary, with some travelers reporting simpler checks than others.