Outdoor cal problem or sun burn?

this is beginning of potassium deficit. most likely is due to buildup of salts and pH change in the pot. review your watering habits. when watering, water as much as you get some run off in the bottom tray and then remove the water from the tray. You have the cloth pots, so air is very fast to dry the water. When water is dried, the ph in the soil is very alkaline and this locks the salts to the roots. 1st signs will be potassium deficit. You have to act quick, as lack of potassium will lead to decreased size in buds, lack of smell, low terpen profile. To sort this out, just give more water with good nutrients, until you get good run off in the bottom tray to wash the roots, even twice per day if soil becomes dry in the evenings. Monitor for this not to spread.