I observe that local travel agencies have no idea about the requirements in order to fly to Phuket and hotels often give erroneous information. Always double check!
Qatar cancelled their flights to Phuket because they were not assured that they are allowed to fly into Phuket from on February. It was not a decision by the airline (so I heard).
Without any hesitation they will have another country-wide lockdown. The measures in spring were hugely successful and there is no indication that the government might hesitate.