Question: Why purple tones on the leaves?

si estas cerca de finalizar la floración, es normal, es signo de maduración

Also look at which leaves are purple. If it's the ones closest to the light it might be a warning. And as others have already said, it could just be the strain you are growing. You could look online at photos of your strain to see what they look like.

Quite a few different strains come out with different colours during late flowering. It's nothing to worry about.

What strain is your plant? Many plant phenos make the leaves and buds purple or red. Is this plant a Auto or Photoperiod? What age is the plant? The closer to the end of the flowering phase could cause the purple hues. I hope this helps to answer your question.