Deficiency ? Chlorine from tape water ?

Looks more.like damage from a contact. either a bug or leaf caught when growing. deficiencies seldom create a hole quickly and go through a slow dying off of portions that tend to discolour first. If the spots are a reddy brown and are slowly getting larger , this would usually be a calmag need to correct. With Led lights , we get a leaching of soil calcium and Magnesium. just a by product of the artificial sunlight. With soil , you need to decide wether your going the nutes route or natural soil life organic. If nutes then looking at the fading green , it would suggest the soil is needing a replenish of feed so a mix needs to be made up. They are greedy plants when they get rooted and settled. good luck