At first the leaves mood , leaves should be like praying for the light making like a V shape. Droopy leaves is a sign a photohinibition when you know that your water schedules and environment conditions are right.
Then the temperature at canopy level, 21°C is the perfect temperature.
And finally and diagnosis of the petioles leaves and leaves stems for purple color , meaning that your plant is burning magnesium and plant photosynthesis process is on a high level.
Spotting lil tiny rust spots on the leaves when you know that your magnesium supplements is right, means that the symptoms are very advanced