Pot looks pretty dry. I would saturate the pot more, 500 ml is only 1/2 quart and is not enough IMO.
Dry medium can cause ph issues and nutrient issues.
What medium are you growing in? Does it have nutrients in it already? If so then the plant may not of needed feed yet.
Dark, shiny, plastic looking and curled leaves makes me think nitrogen toxicity.
Nitrogen toxicity can make leaves more prone to light stress issues as well.