Currently no international flights are coming into Phuket. Some airlines are still selling them and then cancelling them. It would be safer to fly into BKK and do your quarantine there and then make your way to Phuket. Good luck.
No airline is dictating whether you need a covid test or not. It’s down to the government regulations at your point of entry or transit. Currently Thai govt have stipulated there is no requirement for Thais to have a covid test to enter Thailand. If you are transiting through another country then need to check the requirements of that country - your airline would be able to advise though.
there is still no confirmation of this and it’s not official. Pls follow the embassy advice - currently no Covid test required for Thais entering Thailand.