Good morning
So first thing, the purple stems are completely normal for these purple varieties versus getting red/purple stems from a phosphorus deficiency.
However with the slight discoloration happening between the veins it makes me think the plant might benefit from a little more magnesium(which can actually cause some red stems but i don't think it's causing your red stems) . As for the bright white markings, that may just be irritation from the lights or the heat, if it doesn't spread further i wouldn't worry about it. Continue to keep the airflow up and if you need the room to cool down i get the best success with an intake fan, oscillating fans inside and then an exhaust fan.
Happy growing, love those purple buds coming in.✌️