Why my upper leaves turn purple?

Brother è normale! Più si avvicina alla maturazione e più iniziano ad uscire fuori i colori dell'autunno. .. stanno benissimo. Finiscile con solo acqua vedrai che raccogli Buona ganja💪👍

I'm in agreement with most other answers, either genetics or Night temps are a little low.

the purples just a genetic/ environment thing. doesnt look to be anything nutrient or deficiency/ph

Looks like a fade due to cold outside temperature ❄️🌱 but this should not be a problem!

genetics or night time temperatures. Anything 68F or below can potentially bring out "Autumn" colors. It could also just be genetics and nothing to do with temperature, though low temps will augment the effect, too. nothing to worry about. Assume this is soil? would be extremely rare to have a trace element issue.

Cold night temps and anthocyanins are the cause. Nothing to worry about. It is the fade you asked about in a previous question. She should get more colour in the next few weeks.

She looks wonderful and happy, don't worry about that she is just sweetening up the flavour for you, a little chill at nights can cause the pigmentation to change slighlty. The plant mainly uses chlorophyll which makes leaves appear green. The plant is switching some of that green for purple pigment called anthocyanin.