What is the first arrival port in Thailand if I have a layover in Phuket but disembark in Bangkok?

The question seeks clarification on what constitutes the 'first arrival port' in Thailand when layover and immigration occur in different locations. Although the questioner lands in Phuket, they will disembark and complete their quarantine in Bangkok, leading to potential confusion regarding the correct port for entry documentation. Community responses suggest that Bangkok is considered the first arrival port since that's where immigration and customs will be processed.