What should I put as my last port of embarkation when flying to Thailand from Malaysia?

When filling out the last port of embarkation for your flight to Thailand, you should indicate the last country you leave before arriving in Thailand. In your case, if you are flying from Malaysia, you would enter Malaysia as your last port of embarkation. However, if you are considering the travel sequence, any recent countries prior to Malaysia, such as Japan or Ho Chi Minh, might also be relevant depending on your flight route and documentation.