Problems

It looks like Ca deficency to me...

To me it looks like there was remaining water on the leafs, when the sun came out later. With the weather we had the last days (always changing from rainy to sunny) this would be totally possible. This remaining water acts as a magnifying glass and burns the leaf at those spots. The rather round, brown spots that get darker towards the center support that theory. I hope, I could help. Cheers💪

Rain water is the best but coco which it almost certainly looks like should never be given plain water,unless its the flush before harvest.Soil evry other water and coco every water.Always leave tap water to stand for 24hrs,if you're using microbes or anything organic.Chlorine killks beneficial microbes which leaves your plant open to the bad microbes and fungi.

Could need some calcium. Maybe leaves were still wet and got a little sunburn. Could be a pH issue.