This is the information I found:
"From 1 July, 2022, foreign nationals are only required to show proof of either a certificate of vaccination or a negative RT-PCR or professional ATK test result within 72 hours of travel. These can be in a print or digital format. Random checks will be made on arrivals at Thailand’s international airports or land border checkpoints (in 22 provinces). Unvaccinated/not fully vaccinated travellers who are random checked and who are unable to show proof of a pre-arrival negative test will be required to undergo a professional ATK test at the point of entry."