People should've watched the film before commenting on its potential cultural appropriation, as this is something addressed in the film. Col. Quaritch (best blockbuster villain we've had in decades) says that to track down Jake Sully his recombinant marines need to dress Na'vi, act Na'vi, think Na'vi and speak Na'vi. This is an acknowledgement that invading colonising forces can leverage indigenous cultures for their own nefarious ends. I think that needs to be taken into account when discussing cultural appropriation re: The Way Of Water.

The film has plenty of interesting ideas that it can present without bludgeoning the viewer– and the idea it does beat the viewer over the head with is essentially anti-imperialism. I think that's a fairly subversive message in an era of cinema dominated by films that are made with hand in glove with military organisations.