Hi @George something similar appeared in my plants. Last week the temperature reached 35 ° C, with high humidity (I don’t have a meter). This week, it dropped to 10 ° C, and extremely dry, for a few days.
I water every 3 days with biofertilizer and cow urine for fertilization, because as it is in the soil I never saw it dry.
Could it be a momentary excess of nutrients that the plant eliminated through the leaf and dried, leaving some salt that caused the stains? I am saying what I observed in my plants, because they all have, practically the same soil, the same fertilization.
Another observation is that the plants that had the spots were chosen by the leaf-cutting ants. Proving the fact that pests usually attack sick / deficient plants …
We continue …