UPDATE 25/02/22: Final Fantasy composer Nobuo Uematsu has explained why real singing was added to the opera scene in Final Fantasy 6 pixel remaster.
ORIGINAL STORY 21/02/22: Final Fantasy 6 pixel remaster will add actual singing to its famous opera scene.
It remains to be seen whether this new opera scene will fit amongst the rest of the game.
The Final Fantasy 6 pixel remaster is due out on mobile and Steam on 23rd February, bringing updated art, a rearranged score, and quality of life improvements.