Sorting one case
Answer in your head first.
Someone says their salah has gone empty, and also that they have stopped cooking, stopped seeing friends, and that their favourite food tastes of nothing. Which of the four is that closest to?
Depression, not futoor. The tell is that the flatness is not confined to worship. When food, people and work have all gone the same way, worship has gone flat along with everything else, and treating that as a spiritual problem sends a person to more religious effort when what they need is a doctor.